revert r1780909 and r1773397 ProxyPass ! perdir

r1773397 had a regression and the whole thing is fishy
to shoehorn the current ProxyPass ! syntax into.



add no-proxy envvar for mod_proxy

replacement for ProxyPass /path ! when ProxyPass is in
location context.


Submitted by: covener
Reviewed by: covener, jim, jorton


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1782332 13f79535-47bb-0310-9956-ffa450edef68