Make mod_dav_svn's handling of POST errors more like mod_dav's
handling of errors for other requests.  This makes MKACTIVITY
and POST return the same underlying errors to the client.

* subversion/mod_dav_svn/repos.c
  (handle_err): New, based on mod_dav's dav_handle_err.
  (dav_svn__method_post): Call handle_err.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1468347 13f79535-47bb-0310-9956-ffa450edef68