[JDK 8u] Build fails with glibc 2.32

Code in OpenJDK 8u still references sys/sysctl.h in some places. With the release of glibc 2.32 sys/sysctl.h will be removed for Linux. This makes the build fail like so:

/builddir/build/BUILD/java-1.8.0-openjdk-1.8.0.242.b08-3.fc33.x86_64/openjdk/jdk/src/solaris/native/java/net/PlainDatagramSocketImpl.c:44:10: fatal error: sys/sysctl.h: No such file or directory
   44 | #include <sys/sysctl.h>
      | ^~~~~~~~~~~~~~
compilation terminated.
gmake[2]: *** [lib/NetworkingLibraries.gmk:62: /builddir/build/BUILD/java-1.8.0-openjdk-1.8.0.242.b08-3.fc33.x86_64/bootbuild/jdk8.build/jdk/objs/libnet/PlainDatagramSocketImpl.o] Error 1
gmake[2]: *** Waiting for unfinished jobs....
/builddir/build/BUILD/java-1.8.0-openjdk-1.8.0.242.b08-3.fc33.x86_64/openjdk/jdk/src/solaris/native/java/net/PlainSocketImpl.c:46:10: fatal error: sys/sysctl.h: No such file or directory
   46 | #include <sys/sysctl.h>
      | ^~~~~~~~~~~~~~
compilation terminated.

This was fixed in later JDKs by a clean-up patch in JDK-8167481