Merge r1588330 from trunk:

Prevent an external proxy from presenting an internal proxy
in mod_remoteip.c. PR 55962.

Submitted by: mrumph
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1730684 13f79535-47bb-0310-9956-ffa450edef68