Fix a major security problem with double-reverse lookup checking.

Previously, a client connecting over IPv4 would not be matched
properly when the server had an IPv6 listening socket.

PR:	      7407
Submitted by: Taketo Kabe <kiabe@sra-tohoku.co.jp>
Reviewed by:  Jeff Trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@88561 13f79535-47bb-0310-9956-ffa450edef68