Revision 857623

Add the Last-Modified HTTP header to the response as encouraged by
section 13.3.4 of RFC 2616.


* subversion/mod_dav_svn/repos.c
  (RESOURCE_LACKS_ETAG_POTENTIAL): A new macro which returns whether
   the DAV resource lacks potential for generation of an ETag.

  (get_last_modified): A new function used when setting HTTP headers
   in preparation for generating the response which includes the last
   modification time of the requested resource.

  (dav_svn_getetag): Factored complex conditional out into the
   RESOURCE_LACKS_ETAG_POTENTIAL() macro, which is also used by the
   new get_last_modified() function as the heuristic in determining
   whether the Last-Modified header is generated.

  (dav_svn_set_headers): Use httpd's API for setting the modification
   time for request_rec, and its corresponding Last-Modified header.


Suggested by: Sergey Proskurnya <alaley@gmail.com>
              kon
              gstein
              Michael Sinz <Michael.Sinz@sinz.org>