gst-ffmpeg: drop .bbappend, moved to oe-core

* http://git.openembedded.org/openembedded-core/commit/?id=aab668fbba25d3e590e4182224b7b064d7705c5b
* you need to add orc to PACKAGECONFIG if you want to continue
  using it
* PRINC was dropped, oe-core commit had sufficient PR bump and
  this is going in almost simultaneously

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-oe/recipes-multimedia/gstreamer/gst-ffmpeg_0.10.13.bbappend

@@ -1,6 +0,0 @@
-PRINC := "${@int(PRINC) + 2}"
-
-# Build against external libav instead of using the builtin one.
-# On architectures like ARM the libav recipe enables a lot more optimizations
-DEPENDS += "libav orc"
-EXTRA_OECONF += " --with-system-ffmpeg "