Backport proxy_util fix to select worker (jim)

http://svn.apache.org/viewcvs.cgi/httpd/httpd/trunk/modules/proxy/proxy_util.c?rev=356030&view=diff&r1=356030&r2=332306


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@368708 13f79535-47bb-0310-9956-ffa450edef68