Abstract out (kinda) MSG_PEEK. This way when we

actually update APR and apr_socket_recvfrom()
to know about APR_MSG_OOB, APR_MSG_PEEK, etc...
this code won't need to be adjusted. Also,
make nicer for 2.2 backport.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@535354 13f79535-47bb-0310-9956-ffa450edef68