ra_serf: Follow up r32417. Also add the DAV headers to the PROPFIND requests,  which ra_serf handles with specific code.
ra_serf: Follow up r32417. Also add the DAV headers to the PROPFIND requests, 
which ra_serf handles with specific code.

* subversion/libsvn_ra_serf/propfind_buckets.c
  (become_request): set DAV headers to inform the server of the client's
   capabilities.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@873278 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion