In ra serf: decouple the code that implements svn_ra_get_lock() from the code that
implements svn_ra_lock() and svn_ra_unlock(). This fixes a few error messages for
unlikely http response codes for get_lock and allows further refactoring for lock
and unlock.

* subversion/libsvn_ra_serf/getlock.c
  New file. Copied from locks.c.
  (lock_info_t): Remove two variables.
  (locks_ttable): Remove invalid transition.
  (set_lock_headers,
   determine_error): Remove functions.
  (handle_lock): Remove specialized error handling.
  (create_lock_body): Remove function.
  (svn_ra_serf__get_lock): Use standard error reporting and extend with
    handling as we did for neon.
  (svn_ra_serf__lock): Remove function.
  (unlock_context_t): Remove struct.
  (set_unlock_headers,
   svn_ra_serf__unlock): Remove function.

* subversion/libsvn_ra_serf/lock.c
  New file. Copied from locks.c.
  (unnamed enum): Remove unused values.
  (lock_info_t): Rename to...
  (lock_ctx_t): ... this.
  (locks_ttable): Remove invalid transitions.
  (locks_expected_status): Remove variable.
  (locks_closed,
   set_lock_headers,
   handle_lock): Update caller.
  (create_getlock_body,
   setup_getlock_headers): Remove function.
  (create_lock_body): Update caller.
  (svn_ra_serf__get_lock): Remove function.
  (svn_ra_serf__lock): Update caller.

* subversion/libsvn_ra_serf/locks.c


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1551910 13f79535-47bb-0310-9956-ffa450edef68