res_fax: Resolve T38 gateway frame leak.

When frames are translated by a fax gateway they need to be freed.  The
existing call to ast_frfree was unreachable.  This change reorganizes
fax_gateway_framehook to ensure that ast_frfree is called when needed.

ASTERISK-24457 #close
Reported by: Corey Farrell
Review: https://reviewboard.asterisk.org/r/4115/
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Merged revisions 426527 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 426528 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 426529 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@426530 f38db490-d61c-443f-a65b-d21fe96a405b
bridge_builtin_features: Add missing channel locks around ast_get_chan_features_general_config().

The feature_automonitor() and feature_automixmonitor() functions were not
locking the channel around ast_get_chan_features_general_config().
Accessing the channel datastore list without the channel locked is a good
way to corrupt the list or follow the pointer chain into oblivion.
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Merged revisions 426531 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 426552 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@426553 f38db490-d61c-443f-a65b-d21fe96a405b