ra_serf: Properly advertise gzip support for GET requests with delta base, in addition to saying that we accept svndiff1 and svndiff0.
ra_serf: Properly advertise gzip support for GET requests with delta
base, in addition to saying that we accept svndiff1 and svndiff0.

There is no need to hide gzip support if the client is interested in
compression.  And it also allows a server to choose between various ways
of sending compressed deltas, which could either be compressed with
svndiff1, or a delta itself could be uncompressed, but the whole
response could be, for instance, compressed with mod_deflate.

* subversion/libsvn_ra_serf/update.c
  (headers_fetch): Use svn_ra_serf__setup_svndiff_accept_encoding()
   helper to advertise gzip, svndiff1 and svndiff0 support.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1791283 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion