This could save some cycles since skin detection is used in multiple
places in vp9.
1~2% speed up on ARM.
Change-Id: I86b731945f85215bbb0976021cd0f2040ff2687c
Add function to compute skin map for a given block, as its
used in several places (cyclic refresh, noise estimation, and denoising).
Change-Id: Ied622908df43b6927f7fafc6c019d1867f2a24eb
Simple skin detection, from vp8; works reasonable on most of the
RTC clips, but could miss sometimes.
Added debug flag to write out skin map over source input.
Change-Id: I2caea7592f1c459047aac46627eeb24a94946464
