On the authzperf branch: Make the in-place string function a private API,
the authz parser will need it.

* subversion/libsvn_repos/authz.h
  (svn_authz__reverse_string): New prototype.
* subversion/libsvn_repos/authz_parse.c
  (svn_authz__reverse_string): Move implementation here from authz.c.
* subversion/libsvn_repos/authz.c
  (reverse_string): Remove. Update all uses to svn_authz__reverse_string.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/authzperf@1618826 13f79535-47bb-0310-9956-ffa450edef68