Merge r1748047 from trunk:

mod_dav: Add dav_begin_multistatus, dav_send_one_response,
dav_finish_multistatus, dav_send_multistatus, dav_handle_err, 
dav_failed_proppatch, dav_success_proppatch to mod_dav.h.

Submitted by: minfrin
Reviewed by: minfrin, jim, ylavic


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1756561 13f79535-47bb-0310-9956-ffa450edef68