libvpx: Support setting color range for vp9.

Pass through color range to vp9 encoder. Parse color range in libvpxdec.c.

Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Sasi Inguva <isasi@google.com>
Signed-off-by: James Almer <jamrial@gmail.com>