mod_status: PR60647: ACC per connection not available w/ event MPM

trunk patch: http://svn.apache.org/r1780280
2.4.x patch: svn merge -c 1780280 ^/httpd/httpd/trunk .
              (minus CHANGES and ap_mmn.h)
+1: jailletc36, jim, rjung


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1860128 13f79535-47bb-0310-9956-ffa450edef68