Fix the Accept-Encoding header format.
Fix the Accept-Encoding header format.

Reported by: George Schizas <gschizas{_AT_}gmail.com>

* subversion/libsvn_ra_serf/update.c:
  (setup_update_report_headers): use "," between format types


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1497551 13f79535-47bb-0310-9956-ffa450edef68

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