Fix compilation with --disable-everything --enable-decoder=rawvideo.
avfilter/vf_colormatrix: fix memleak on error

Fixes CID1197065
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'cehoyos/master'

* cehoyos/master:
  Fix compilation with --disable-everything --enable-decoder=rawvideo.

Merged-by: Michael Niedermayer <michaelni@gmx.at>