Fixed proxy-pass-through feature of mod_rewrite; Added error logging

information for case where proxy module is not available. [Marc Slemko]

Submitted by:	Marc Slemko
Reviewed by:	Dean Gaudet, Ralf S. Engelschall


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@78988 13f79535-47bb-0310-9956-ffa450edef68