Add OmitPID keyword on Mutex directive to suppress the

addition of the parent pid to the generated lock file
name.

Change the Mutex directive syntax from

  Mutex default|mutex-name mechanism

to

  Mutex mechanism [default|mutex-name] ... [OmitPID]

as suggested by wrowe.  (Thanks!)



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@886154 13f79535-47bb-0310-9956-ffa450edef68