Add Asterisk Version to core show locks

Assist with reporting 'core show locks' when submitting bug reports.

Example below:

===========================
== SVN-branch-1.8-...
== Currently Held Locks
===========================


(closes issue ASTERISK-21743)

Reported by: alecdavis
Tested by: alecdavis
alecdavis (license 585)
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Merged revisions 387294 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 387295 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@387296 65c4cc65-6c06-0410-ace0-fbb531ad65f3