Backport:

Backport:

*) core: Add ap_pre_connection() as a wrapper to ap_run_pre_connection()
   and use it to prevent that failures in running the pre_connection
   hook cause crashes afterwards.
   Trunk version of patch:
      https://svn.apache.org/r1893497
      https://svn.apache.org/r1893507
   Backport version for 2.4.x of patch:
     https://patch-diff.githubusercontent.com/raw/apache/httpd/pull/269.diff
   Can be applied via apply_backport_pr.sh 269.
   +1: rpluem, icing, ylavic

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1893654 13f79535-47bb-0310-9956-ffa450edef68