Don't remove the Content-Length from responses in mod_proxy

PR: 8677
Obtained from:
Submitted by:	Brian Pane
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@98425 13f79535-47bb-0310-9956-ffa450edef68