Update gstreamer1 to upstream release 1.20.3

PR:		261585
Reviewed by:	riggs,jbeich,tcberner

Differential Revision:	https://reviews.freebsd.org/D36850

textproc/libxml2: bump all LIB_DEPENDS consumers

This is a separate commit to facilitate easier cherry-picking for
quarterly.

PR: 262853, 262940, 262877, 263126
Approved by: fluffy (mentor)

textproc/libxml2: bump all dependencies

This should make sure that all dependent ports will pick
up the new version commited with a13ec21cd733f67a9fc0dc00ab45268bdc236246

One more small cleanup, forgotten yesterday.
Reported by:	lwhsu

Remove # $FreeBSD$ from Makefiles.

Update GStreamer1 ports to 1.12.2.

Rework the adding of dependancies in Mk/bsd.gstreamer.mk.
Previous when using USE_GSTREAMER[1] it would just add the request modules to
BUILD/RUN_DEPENDS. This caused the qa script to complain because the old code
didn't implicit depend on the gstreamer1 and gstreamer1-plugins[-bad] ports for
the libraries they carried, even if they where present via the plugins! The new
code adds implicit depends on these ports so USE_GSTREAMER[1] using ports have
all the libraries included.

* The mad mp3 plugin was removed, mpg123 plugin also provides mp3 decoding.
Switch over ports that used the gstreamer1 mad plugin.
* gtksink plugin renamed -> gtk
* Hook up the sndio plugin into the framework
* Add some indirect dependacies where needed
* Reorder the plugin list in bsd.gstreamer.mk so only one plugin per line. When
changing plugins it doesn't result in multiple lines being changed.
* Remove mentions in bsd.gstreamer.mk of plugins mentions that where removed.
* Depend on libunwind on i386/amd64, GStreamer links to it if it is present.

PR:		220753
Exp-run by:	antoine@

Remove all USE_OPENSSL occurrences.

Sponsored by:	Absolight

Update GStreamer1 to 1.6.2.
Update GStreamer1-vaapi to 0.7.0.

* Spell GStreamer consistently. [1]
* Fix typo in py3kplist in py3-gstreamer1 [1]
* Improve plugins COMMENTS (more improvements welcome)
* Actually include the gstreamer1-libav update this time.

PR:		204204 [1] (based on)
Submitted by:	olivierd@ [1]

Update gstreamer1 ports to 1.6.0.

* gstreamer1-libav now uses ffmpeg from ports.
* New ports:
  * gstreamer1-validate: Tools to detect if elements are not behaving
    as expected, mainly aimed at developers, or advanced debugging.
  * gstreamer1-rtsp-server: Base foundation for building a rtsp
    server ontop of GStreamer
 * Bunch of new plugins like: mpg123, rsvg, libde265, openh264, x265 and dtls.

Release announcement:
 
http://lists.freedesktop.org/archives/gstreamer-announce/2015-September/000357.html

Obtained from:	gnome devel repo