Followup to r18170. Restore APR 1.x compatibility.
Followup to r18170. Restore APR 1.x compatibility.

* subversion/libsvn_fs_base/env.c
  (svn__atomic_cas): New macro, defined differently for APR 0.9.x and 1.x.
  (bdb_cache_init): Change apr_atomic_cas to svn__atomic_cas.
    Also fix comment.

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