Make more cases of http status processing in libsvn_ra_serf use the standard
errors reporting.

* subversion/libsvn_ra_serf/commit.c
  (unexpected_status_error): Move function to util.c and rename.
  (checkout_node): Update caller.
  (proppatch_walker): Add error case to avoid compiler warning.
  (proppatch_resource,
   open_root,
   delete_entry,
   add_directory,
   add_file,
   close_file,
   close_edit
   abort_edit): Update caller.

* subversion/libsvn_ra_serf/getlocks.c
  (svn_ra_serf__get_locks): Explicitly handle results.

* subversion/libsvn_ra_serf/get_lock.c
  (svn_ra_serf__get_lock): Explicitly handle results.

* subversion/libsvn_ra_serf/merge.c
  (svn_ra_serf__run_merge): Verify result locally instead of making the
    single caller do that.

* subversion/libsvn_ra_serf/ra_serf.h
  (svn_ra_serf__run_merge): Remove output argument.
  (svn_ra_serf__error_on_status): Extend documentation.
  (svn_ra_serf__unexpected_status): New function.

* subversion/libsvn_ra_serf/update.c
  (handle_fetch): Use standard unexpected result handling.
  (finish_report): Eagerly handle http status.

* subversion/libsvn_ra_serf/util.c
  (svn_ra_serf__error_on_status): Tweak message.
  (svn_ra_serf__unexpected_status): New function; mostly copied from commits.c.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1553697 13f79535-47bb-0310-9956-ffa450edef68