- Function level improvement (ms):
Functions       ssse3  avx2   Percentage
idct32x32_1024  794    374    52.9%
idct32x32_135   354    169    52.2%
idct32x32_34    197    142    27.9%
idct32x32_1     n/a     26    n/a

- Integrating in default scan order.

Change-Id: I84815112b26b8a8cb800281a1cfb1706342af57d