Merge r732421, r732451 from trunk:

Release the accept mutex after receiving the shutdown signal
in single-process mode.  (That isn't a critical step, but
neatness counts.)

Submitted by: rpleum



prefork: Fix child process hang during graceful restart/stop in
configurations with multiple listening sockets.

PR: 42829
Submitted by: Joe Orton, with some tweaking and testing from me

Reviewed by: trawick, rpluem, jorton, pgollucci



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@739608 13f79535-47bb-0310-9956-ffa450edef68