Merge r1892986, r1892987 from trunk:

Merge r1892986, r1892987 from trunk:

mod_proxy: Follow up to r1892814.

* modules/proxy/proxy_util.c(fix_uds_filename):
  Sanity checks on the configured UDS path, fail with 500 if invalid since
  continuing through proxy processing wouldn't work as expected.

mod_proxy: Follow up to r1892986: APLOGNO()

Stefan get out of this body! :)

Submitted by: ylavic
Reviewed by: rpluem, ylavic, covener

Github: closes #265

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1893101 13f79535-47bb-0310-9956-ffa450edef68