1010102, 101010x, 888x in sw

Same sort of deal as before, now with all three new formats.
While I was at it, I made sure RGBA 8888 and BGRA 8888 both work too.

We don't want the 101010's in lowp, but 888x should be fine.

After looking at the DM images on monitors at work, I decided to
re-enable dither even on 10-bit images.

Looking at the GMs in 888x or 101010x is interesting... I think we must
not be clearing the memory allocated for layers?  Seems like we want to
allocate layers as 8888?

Change-Id: I3a85b4f00877792a6425a7e7eb31eacb04ae9218
Reviewed-on: https://skia-review.googlesource.com/101640
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
16 files changed