AST_EXT_LIB_CHECK has several optional parameters. When an optional parameter
is left empty, [] is used to indicate this. However, this is done in the script
./configure only then, when a further parameter is not empty. For example, when
no extra libraries are needed to test the checked library, parameter 5 is not
mentioned. Except parameter 6 and higher are used, then parameter 5 must be
empty.

However, this general rule was broken
* four times for parameter 5 (extra libs) and
* three times for parameter 4 (header)
as found via the Regular Expression \[\]\). In case of parameter 5, all cases
were changed, because that happened for no reason. In case of parameter 4, an
[] improves readability actually. Therefore for parameter 4, the only case which
did not do it was changed. All this aims to create more consistency: Only do
something different if there is a reason to do so.

Change-Id: I037ef170cf1ad94497151a9ea5071a31c656cafe

The functions behind the flag and the flag itself were removed
from Asterisk 12 as incompatible with the new architecture.

Change-Id: I058493ef7a53ee290fd225bbcbb07bf46b623ccf

Remove symbols that are depreacated and replaced:
* ast_channel_datastore_alloc
* ast_channel_datastore_free
* ast_channel_cmpwhentohangup
* ast_channel_setwhentohangup
* config_text_file_save
* devstate2str
* ast_device_state_changed
* ast_device_state_changed_literal
* ast_verbose_get_by_module

Remove unused symbols:
* channelreloadreason2txt (last used in Asterisk 12).

Remove unused ast_options flags:
* AST_OPT_FLAG_END_CDR_BEFORE_H_EXTEN / ast_opt_end_cdr_before_h_exten
* AST_OPT_FLAG_VERBOSE_MODULE / ast_opt_verb_module
* AST_OPT_FLAG_INITIATED_SECONDS

Change-Id: I841255995d195f8efc1ed47af9c7a2f131c08645

* dahdi_chan_name
* dahdi_chan_name_len
* dahdi_chan_mode
* __manager_event
* dialed_interface_info

Added comment about __progname and environ being needed for FreeBSD to
prevent accidental removal in the future.

Change-Id: I3ae026bc541cd9cb572be2ffa95fc359547642b5

Change-Id: I317a82de976bbdbfe4352c243e32a7bb8f66c377

Change-Id: I140e1137906bbfcdb61c0c6304159be459ad873e

If the two formats on a channel are equal, we don't transcode and since
the generic plc needs slin to work, it doesn't get invoked.

* A new configuration option "genericplc_on_equal_codecs" was added
  to the "plc" section of codecs.conf to allow generic packet loss
  concealment even if no transcoding was originally needed.
  Transcoding via SLIN is forced in this case.

ASTERISK-27743

Change-Id: I0577026a179dea34232e63123254b4e0508378f4

Change-Id: I658141c6ec490a3e866b02d2afea757928ceaabf

Change-Id: I5133ff2ba4e030f9733fb3d050c863d72a22ae6b

This change adds a property to RTP instances to indicate that
REMB support is enabled and that sending/receiving should be
passed through.

This also enables it on video RTP instances in PJSIP if
WebRTC support is enabled.

Finally the goog-remb extension is added to the SDP using
the rtcp-fb attribute to indicate our support for it.

Details about REMB can be found on the draft document for it:
https://tools.ietf.org/html/draft-alvestrand-rmcat-remb-03

Change-Id: I1902dda1c0882bd1a0d71b2f120684b44b97e789