Allow locks to be inherited through a masquerade without causing starvation.

(closes issue #14859)
 Reported by: atis
 Patches: 
       20090821__issue14859.diff.txt uploaded by tilghman (license 14)
       20090925__issue14859__1.6.1.diff.txt uploaded by tilghman (license 14)
 Tested by: atis, tilghman


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@221044 65c4cc65-6c06-0410-ace0-fbb531ad65f3