Switch SkBitmapProcState's SkFractionalInt to 32.32.

16 bits are not enough to hold the integral part of fx in
Clamp_S32_opaque_D32_nofilter_DX_shaderproc.

Weirdly, no GM diffs on my desktop.

BUG=skia:3096

Review URL: https://codereview.chromium.org/733163003
2 files changed