certain types of mutexes (particularly SysV semaphores), we
should expect to occasionally fail to obtain or release the
mutex during restart processing.

These mutex failures seem to be a pretty rare occurrence, but
it was fatal.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95665 13f79535-47bb-0310-9956-ffa450edef68