Skia: Fix special case in D32_A8_Opaque and _Black

Neon optimization implemented for D32_A8_Opaque and D32_A8_Black
is not using the right mask for width>=2 and width<4 case. This
is fixed in this patch by handling 4 different cases: width >=8,
4<=width<7, 2<=width<4, and residual case.

Change-Id: I20bf1cc28eac08402d4133aac663ebfc393edbe0
NEON optimized blitter S32_Opaque_D32_filter_DX

Re-work for latest code base as the -Os compiler options is added.
Overwrite the optimization level at function level.

Change-Id: I732fea7f02f775a4b06884460dea2887d4108820