move unspecialized routines out of SkOpts

No src/opts/SkOpts_foo.cpp ever replaces these function pointers with
a specialized version, so there's no value to the indirection.

I kind of want to rewrite most of this, but I've not done that here.
It's all just the same code moved around.

Change-Id: Iecb81a64aff3e9ed18c1a3c6d2eb1a6e94e966de
Reviewed-on: https://skia-review.googlesource.com/c/165400
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
7 files changed