gstreamer: gst-ffmpeg: fix build issues for libav

gstreamer: gst-ffmpeg: fix build issues for libav

1.The included libav configure is not generated by autotools
  modify recipe to use correct toolchain wrapper with configure

2.add bzip2 dependency explicitly.
  or configure will detect whether libbz2 is installed, if bzip2
is triggered earlier then it will be detected, if not then won't

3.backport libav_e500mc.patch from upstream to patch configure to
disable-altivec if it is e500mc.

4.move the GSTREAMER_DEBUG to libav's configure, it is not the
option for the main configure.

(From OE-Core rev: a6384b2bd1d608506557ce151135edffa4cb5e0b)

Signed-off-by: Yao Zhao <yao.zhao@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>