Update gstreamer1 to 1.16.2.

- The spc plugin was removed inflavor for the gsm plugin.
- Added in tree qt plugin.

Changelog: https://gstreamer.freedesktop.org/releases/1.16/#1.16.2

Update net-im/fractal to 4.2.2 to support GStreamer 1.16 (approved by
maintainer)

Thanks to antoine@ for the exp-run.

PR:		239386

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@