vp8-denoiser: Avoid doing the mcomp if we don't denoise.

Avoid doing the mcomp in denoiser if we don't denoise the
block (because of motion/SSE/skin threshold, etc).
This can reduce encoding time (with denoiser enabled) by ~1.5-2%.

Change-Id: Ia699b68dfd37b89cdf3a82b8aa40e8c8f98a3d4f
1 file changed