Clean up two unlaunched SSE 4.1 8888 blits.

This code was running on our bots but never in Chrome.
That's a bad state to be in.

My plan here use to be to redesign how our 8888 blits worked in SSE 4.1, mainly
for perfect correctness but also for speed, then to spread what I learned there
to SSE2, AVX+, and NEON.

I have since lost interest in changing any aspect of how our legacy 8888 blits
work.  There's not much point in making them a bit or two more correct when the
math is fundamentally wrong.

This will cause many diffs in Gold, none perceptible.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2062853002
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review-Url: https://codereview.chromium.org/2062853002
1 file changed