Merge r1543174, r1560367, r1560546, r1560689, r1560979, r1561137, r1561660 from trunk:

Correct logic... if this is a UDS socket, then bypass all
this.

make mod_rewrite and mod_proxy UDS work together...

Adjust url as required, following what we did to r->filename.
Save some cycles when searching...

Tuck away UDS path in request-rec, since worker isn't
thread-safe. Protect from NULL refs.

Reflow logic... pull UDS stuff out

handle leak. thx to Y^2

r->filename should maintain the proxy: prefix for PHP-FPM
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1588494 13f79535-47bb-0310-9956-ffa450edef68