De-proc Color32

De-proc Color32

Also strips SK_SUPPORT_LEGACY_COLOR32_MATH,
which is no longer needed.

Seems handy to have SkTypes include the relevant intrinsics when
we know we've got them, but I'm not married to it.

Locally this looks like a pointlessly small perf win, but I'm mostly
keen to get all the code together.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/376e9bc206b69d9190f38dfebb132a8769bbd72b

Review URL: https://codereview.chromium.org/1104183004