As part of the compiler upgrade project (JDK-8076053), an additional warning had to be disabled for libt2k (JDK-8134156):

/localhome/hg/jdk9-dev-full/jdk/src/closed/java.desktop/share/native/libt2k/t2k/ttHints/HintGlyph.c: In function 'TTScalerHintGlyph':
/localhome/hg/jdk9-dev-full/jdk/src/closed/java.desktop/share/native/libt2k/t2k/ttHints/HintGlyph.c:156:49: error: variable 'theGlyph' might be clobbered by 'longjmp' or 'vfork' [-Werror=clobbered]
                 perGlyph* theGlyph=0L;
                                                 ^

However, disabling the warning is just a temporary fix. The problem should be fixed properly, and the line:

 DISABLED_WARNINGS_gcc := clobbered, \

removed from make/closed/lib/Awt2dLibraries.gmk.