[proposal for 1.0 API] change APR not to export OS symbols to applications

[Jeff Trawick]

Currently, APR exports unqualified OS symbols to applications on some 
platforms.  These symbols include HPUX11=1, HPUX=1, NETBSD=1, SOLARIS2=8 
(or whatever), and others.  These shouldn't be added to compile flags since

1) it can interfere with application defines
2) they aren't properly qualified with APR_
3) they aren't consistently implemented
If we actually require some of these symbols in public header files, 
that probably needs to be fixed.  If the APR implementation needs it 
somewhere, something should be placed in apr_private.h instead.

Comments?