chan_iax2: Several media format fixes.

* Fixed the iax.conf bandwidth option.  This is the root cause of
ASTERISK-24150.

* Added checks in iax2_request() to ensure that there are actual formats
requested for the new channel to prevent any more fracks from issues like
ASTERISK-24150.  This is a consequence of the iax.conf bandwidth option
not working.

* Fixed struct iax2_codec_pref.order member size mismatch issue when
converting to and from the codec preference order list passed over the
wire.  In addition the values sent over the wire are now compatible with
previous Asterisk versions.

* Fixed several issues dealing with the struct iax2_codec_pref members.
Off-by-one, array limit errors, and the order/framing members always need
to be updated together.

* Made iax2_request() setup the channel's native format preference order
according to the user's wishes.  The new media format strategy needs the
order specified earler.

* Fixed usage of ast_format_compatibility_bitfield2format().  The function
can return NULL if the bitfield was not associated with a function.

* Deleted dead code iax2_codec_pref_getsize() and
iax2_codec_pref_setsize().

* Made iax2_parse_allow_disallow() and iax2_codec_pref_string() call
iax2_codec_pref_to_cap() instead of inlining it.

* Made IAX_CAPABILITY_MEDBANDWIDTH, IAX_CAPABILITY_LOWBANDWIDTH, and
IAX_CAPABILITY_LOWFREE constants again as they were in Asterisk v1.8.

* Renamed prefs to prefs_global so it won't get confused with the local
pref versions.

* Fixed too small buffer in handle_cli_iax2_show_peer().

* Fixed ast_cli() calls in handle_cli_iax2_show_peer() to output complete
lines.

* Changed struct create_addr_info.prefs to be struct iax2_codec_pref as an
optimization so iax2_request() and iax2_call() do less work.

* Fixed a potential deadlock in ast_iax2_new() on an off-nominal path when
the pbx could not get started.

* Made set_config() setup a local prefs list along side the local
capability format bitfield.  Once the config is loaded, then the local
copies are put into the global versions.

* Fix unininialized codec_buf in function_iaxpeer().

ASTERISK-24150 #close
Reported by: Scott Griepentrog

Review: https://reviewboard.asterisk.org/r/3890/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@420364 f38db490-d61c-443f-a65b-d21fe96a405b