Add MALLOC_DEBUG atexit unreleased malloc memory summary.

Add MALLOC_DEBUG atexit unreleased malloc memory summary.

* Adds the following CLI commands to control MALLOC_DEBUG reporting of
unreleased malloc memory when Asterisk is shut down.
memory atexit list on
memory atexit list off
memory atexit summary byline
memory atexit summary byfunc
memory atexit summary byfile
memory atexit summary off

* Made check all remaining allocated region blocks atexit for fence
violations.

* Increased the allocated region hash table size by about three times.  It
still isn't large enough considering the number of malloced blocks
Asterisk uses.

* Made CLI "memory show allocations anomalies" use
regions_check_all_fences().

Review: https://reviewboard.asterisk.org/r/2196/
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Merged revisions 376788 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 376789 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@376790 65c4cc65-6c06-0410-ace0-fbb531ad65f3