*) mod_session: Strip Session header when SessionEnv is on.

     trunk patch: http://svn.apache.org/r1824390
     2.4.x patch: trunk works (modulo CHANGES)
     +1: ylavic, rpluem, minfrin


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1824477 13f79535-47bb-0310-9956-ffa450edef68