* prevent a fork bomb if the accept mutex is clobbered by exiting with

  APEXIT_CHILDSICK if the worker process hasn't served any requests
* move the accept mutex error leg into its own function to take advantage of
  common code and to keep rarely executed instructions out of the mainline
  instruction cache.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@815915 13f79535-47bb-0310-9956-ffa450edef68