Fix handling of IPv6 numeric strings in mod_proxy.

(Some such operations would work if port was specified
in url due to way parsing was performed, finding last ':'
and considering everything after as the port.)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@103698 13f79535-47bb-0310-9956-ffa450edef68