We are seeing slowdebug build failures of 11.0.10+1 due to link issues of libharfbuzz.so:

Linking libharfbuzz.so
( /bin/rm -f /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log && /usr/bin/g++ -Wl,--hash-style=both -Wl,-z,defs -Wl,-z,relro -Wl,-z,now -Wl,-z,noexecstack -m64 -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.base -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.base/server -shared -Wl,--exclude-libs,ALL -Wl,-z,origin -Wl,-rpath,\$ORIGIN -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop -Wl,-soname=libharfbuzz.so -o /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.so @/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/_BUILD_LIBHARFBUZZ_objectfilenames.txt -lm -static-libstdc++ -static-libgcc > >(/usr/bin/tee -a /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log) 2> >(/usr/bin/tee -a /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log >&2) || ( exitcode=$? && /bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log /home/openjdk/jdk11u/build/slowdebug/make-support/failure-logs/support_native_java.desktop_libharfbuzz_BUILD_LIBHARFBUZZ_link.log && /bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.cmdline /home/openjdk/jdk11u/build/slowdebug/make-support/failure-logs/support_native_java.desktop_libharfbuzz_BUILD_LIBHARFBUZZ_link.cmdline && exit $exitcode ) ) ; /usr/bin/objcopy --only-keep-debug /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.so /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.debuginfo
/bin/rm -f /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d
cd /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz && /bin/cat *.d > /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d.tmp
g++: unrecognized option '-static-libstdc++'
cd /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz && /bin/cat *.d.targets | /bin/sort -u >> /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d.tmp
/bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d.tmp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d.old
/bin/mv /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d.tmp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ.d
/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/hb-aat-layout.o: In function `AAT::KerxTable<AAT::kerx>::apply(AAT::hb_aat_apply_context_t*) const':
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `AAT::kerx::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `AAT::kerx::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `AAT::kerx::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `AAT::kerx::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:926: undefined reference to `AAT::kerx::tableTag'
/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/hb-aat-layout.o:/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:926: more undefined references to `AAT::kerx::tableTag' follow
/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/hb-ot-layout.o: In function `AAT::KerxTable<OT::KernOT>::apply(AAT::hb_aat_apply_context_t*) const':
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernOT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernOT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernOT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernOT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:926: undefined reference to `OT::KernOT::tableTag'
/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/hb-ot-layout.o:/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:926: more undefined references to `OT::KernOT::tableTag' follow
/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/hb-ot-layout.o: In function `AAT::KerxTable<OT::KernAAT>::apply(AAT::hb_aat_apply_context_t*) const':
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernAAT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernAAT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernAAT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:894: undefined reference to `OT::KernAAT::tableTag'
/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:926: undefined reference to `OT::KernAAT::tableTag'
/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/hb-ot-layout.o:/home/openjdk/jdk11u/src/java.desktop/share/native/libharfbuzz/hb-aat-layout-kerx-table.hh:926: more undefined references to `OT::KernAAT::tableTag' follow
collect2: ld returned 1 exit status
gmake[3]: *** [/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.so] Error 1
gmake[3]: Leaving directory `/home/openjdk/jdk11u/make'
gmake[2]: *** [java.desktop-libs] Error 1
gmake[2]: Leaving directory `/home/openjdk/jdk11u'

As it turns out JDK-8249821 got backported to 11.0.10 and that change also includes some LDFLAGS changes. Previously the link when it was part of libfontmanager.so was:

Linking libfontmanager.so
( /bin/rm -f /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libfontmanager/BUILD_LIBFONTMANAGER_link.log && /usr/bin/g++ -Wl,--hash-style=both -Wl,-z,relro -Wl,-z,now -Wl,-z,noexecstack -m64 -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.base -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.base/server -shared -Wl,--exclude-libs,ALL -Wl,-z,origin -Wl,-rpath,\$ORIGIN -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop -Wl,-soname=libfontmanager.so -o /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libfontmanager.so @/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libfontmanager/_BUILD_LIBFONTMANAGER_objectfilenames.txt -lfreetype -lawt -ljava -ljvm -lm -static-libstdc++ -static-libgcc > >(/usr/bin/tee -a /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libfontmanager/BUILD_LIBFONTMANAGER_link.log) 2> >(/usr/bin/tee -a /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libfontmanager/BUILD_LIBFONTMANAGER_link.log >&2) || ( exitcode=$? && /bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libfontmanager/BUILD_LIBFONTMANAGER_link.log /home/openjdk/jdk11u/build/slowdebug/make-support/failure-logs/support_native_java.desktop_libfontmanager_BUILD_LIBFONTMANAGER_link.log && /bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libfontmanager/BUILD_LIBFONTMANAGER_link.cmdline /home/openjdk/jdk11u/build/slowdebug/make-support/failure-logs/support_native_java.desktop_libfontmanager_BUILD_LIBFONTMANAGER_link.cmdline && exit $exitcode ) ) ; /usr/bin/objcopy --only-keep-debug /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libfontmanager.so /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libfontmanager.debuginfo

Now it's:

Linking libharfbuzz.so
( /bin/rm -f /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log && /usr/bin/g++ -Wl,--hash-style=both -Wl,-z,defs -Wl,-z,relro -Wl,-z,now -Wl,-z,noexecstack -m64 -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.base -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.base/server -shared -Wl,--exclude-libs,ALL -Wl,-z,origin -Wl,-rpath,\$ORIGIN -L/home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop -Wl,-soname=libharfbuzz.so -o /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.so @/home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/_BUILD_LIBHARFBUZZ_objectfilenames.txt -lm -static-libstdc++ -static-libgcc > >(/usr/bin/tee -a /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log) 2> >(/usr/bin/tee -a /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log >&2) || ( exitcode=$? && /bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.log /home/openjdk/jdk11u/build/slowdebug/make-support/failure-logs/support_native_java.desktop_libharfbuzz_BUILD_LIBHARFBUZZ_link.log && /bin/cp /home/openjdk/jdk11u/build/slowdebug/support/native/java.desktop/libharfbuzz/BUILD_LIBHARFBUZZ_link.cmdline /home/openjdk/jdk11u/build/slowdebug/make-support/failure-logs/support_native_java.desktop_libharfbuzz_BUILD_LIBHARFBUZZ_link.cmdline && exit $exitcode ) ) ; /usr/bin/objcopy --only-keep-debug /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.so /home/openjdk/jdk11u/build/slowdebug/support/modules_libs/java.desktop/libharfbuzz.debuginfo

The keen-eyed will notice that the latter includes "-Wl,-z,defs" while the former does not.