pbx.c: fix confused match caller id that deleted exten still in hash

This fixes a bug where a zero length callerid match adjacent to a no
match callerid extension entry would be deleted together, which then
resulted in hashtable references to free'd memory.  A third state of
the matchcid value has been added to indicate match to any extension
which allows enforcing comparison of matchcid on/off without errors.

(closes issue AST-1235)
Reported by: Guenther Kelleter
Review: https://reviewboard.asterisk.org/r/2930/
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Merged revisions 401959 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 401960 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 401961 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@401962 65c4cc65-6c06-0410-ace0-fbb531ad65f3