dahdi show channels output slices the callerid (which is dnid copied over on
PRI channels). If the channel naming structures look like:

 'DAHDI/i1/1408409XXXX-6'

then the output slices 1408409XXXX down to 1408409XXX. This patch just opens
it up to 15 chars so you can see the whole thing.

(closes issue ASTERISK-22918)
Reported by: outtolunc
Patches:
     svn_chan_dahdi.c.format12_15.diff.txt uploaded by outtolunc (license 5198)
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Merged revisions 404784 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 404785 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 404786 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@404787 65c4cc65-6c06-0410-ace0-fbb531ad65f3