SkLiteDL: a little spring cleaning

  - kill off optimizeFor() now that we know it's broken and have a better way;
  - simplify makeThreadsafe() a bit: we're not calling it anyway.

This sort of earns me back some crazy code currency,
which I am going to try to spend making reset() faster.

If anything, this appears to make makeThreadsafe() _faster_.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2254913002

Review-Url: https://codereview.chromium.org/2254913002
2 files changed