Merge r1802618, r1820808 from trunk:

core, mpm_event: Add ap_update_sb_handle() to avoid a small memory leak of
sizeof(ap_sb_handle_t) when re-entering event's process_socket().


Follow up to r1802618: CHANGES entry.


Proposed by: ylavic
Reviewed by: ylavic, icing, jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1821069 13f79535-47bb-0310-9956-ffa450edef68