Recorded merge of revisions 372764 from http://svn.asterisk.org/svn/asterisk/branches/10

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Warn on CLI when UDPTL init fails

This adds a CLI warning when a SDP offer is rejected due to UDPTL
initialization failure. Previously, there was no indication of the
reason for offer rejection in this case.

(closes issue ASTERISK-20357)
Reported-by: Francesco Usseglio Gaudi
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Merged revisions 372763 from http://svn.asterisk.org/svn/asterisk/branches/1.8

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@372766 65c4cc65-6c06-0410-ace0-fbb531ad65f3