Fix the Windows build.
Fix the Windows build.

* build.conf (libsvn_subr):  Export svn_debug.h.

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