Timout or error on INFO or MESSAGE transaction causes call to be lost.

Timout or error on INFO or MESSAGE transaction causes call to be lost.

When exchanging INFO messages within a call, 4xx error causes the call to
be disconnected although RFC 2976 explicitly states that such transactions
do not modify the state of the dialog.

When exchanging MESSAGE messages within a call, 4xx error causes the call
to be disconnected.  To provide least surprise, we should not disconnect
the call since a MESSAGE is like INFO in this case.  (Implied by RFC 3428
Section 2)

(closes issue ASTERISK-17901)
Reported by: neutrino88

Review: https://reviewboard.asterisk.org/r/1257/
Review: https://reviewboard.asterisk.org/r/1258/

JIRA SWP-3486

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@324481 65c4cc65-6c06-0410-ace0-fbb531ad65f3