gst1-plugins-bad: update plugin licenses

gst1-plugins-bad: update plugin licenses

Update several of the licenses annotated in the gst1-plugins-bad.mk file.

1. Specify GPL-2.0 in license info.
* All of the *.[ch] that specify GPL also specify version 2 or later.

2. Remove GPL from audiovisualizers.
* Changlog notes move from GPL to LGPL. (2015-04-25)
* docs/plugins/inspect/plugin-audiovisualizers.xml claims "LGPL".
* All *.[ch] files under ./gst/audiovisualizers say "GNU Library General Public License".

3. Add GPL to yadif.
* Changelog notes that yadif is "GPL". (2013-02-07)
* docs/plugins/inspect/plugin-yadif.xml claims "GPL".
* All *.[ch] files under ./gst/yadif say "GNU General Public License" except for one "GNU Library General Public License".

4. Remove UNKNOWN from fdk_aac.
* docs/plugins/inspect/plugin-fdkaac.xml claims "LGPL".
* All *.[ch] files under ./ext/fdkaac say "GNU Lesser" or "GNU Library General Public License".

5. Add BSD-2c to dtls.
* docs/plugins/inspect/plugin-dtls.xml claims "BSD".
* All *.[ch] files under ./gst/dtls have BSD-2c text.

6. Add BSD-2c to openh264.
* Changelog notes that openh264 is "BSD-2". (2014-10-03)
* docs/plugins/inspect/plugin-openh264.xml claims "BSD".
* All *.[ch] files under ./ext/openh264 have BSD-2c text.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>