tcptls: Prevent unsupported options from being set

AMI, HTTP, and chan_sip all support TLS in some way, but none of them
support all the options that Asterisk's TLS core is capable of
interpreting. This prevents consumers of the TLS/SSL layer from setting
TLS/SSL options that they do not support.

This also gets tlsverifyclient closer to a working state by requesting
the client certificate when tlsverifyclient is set. Currently, there is
no consumer of main/tcptls.c in Asterisk that supports this feature and
so it can not be properly tested.

Review: https://reviewboard.asterisk.org/r/2370/
Reported-by: John Bigelow
Patch-by: Kinsey Moore
(closes issue AST-1093)
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Merged revisions 383165 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 383166 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@383167 f38db490-d61c-443f-a65b-d21fe96a405b
Make stasis unsubscription functions return NULL

Unsubscribing things in Asterisk seems to very commonly follow with
NULLing out the variable that was unsubscribed. This change makes that
a bit simpler.


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@383168 f38db490-d61c-443f-a65b-d21fe96a405b
Take advantage of the fact that stasis_unsubscribe now returns NULL


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@383169 f38db490-d61c-443f-a65b-d21fe96a405b