mod_rewrite: When evaluating a proxy rule in directory context,

do escape the filename by default, since mod_proxy will not
escape in that case due to the (deliberate) fixup hook ordering.
PR 46428

Backport of r757427 from trunk resp. r773351 from 2.2.x.

Submitted by: jorton/rpluem
Backported by: rjung
Reviewed by: wrowe, humbedooh


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@1469721 13f79535-47bb-0310-9956-ffa450edef68