hold tracking information for mutexes.  Now, the "core show locks" output
will output information about who is holding a rwlock when a thread is
waiting on it.

(closes issue #11279)
Reported by: ys
Patches:
      trunk_lock_utils.v8.diff uploaded by ys (license 281)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@120064 65c4cc65-6c06-0410-ace0-fbb531ad65f3