[ Note from the future: reverted in r981803 ]
[ Note from the future: reverted in r981803 ]

* tools/dev/unix-build/Makefile.svn: OpenBSD recently enabled -Wsystem-headers
   in gcc by default, which causes annoying warnings from OpenBSD's system
   headers during Subversion's build. So use -Wno-system-headers here. I have
   not done this in Subversion's own configure.ac because I am not sure
   whether all compilers support the -Wno-system-headers option.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion