SkNx refactoring

  - add back Sk4i typedef
  - define SSE casts in terms of Sk4i
      * uint8  <-> float becomes uint8  <-> int <-> float
      * uint16 <-> float becomes uint16 <-> int <-> float

    This has the nice side effect of specializing uint8 <-> int
    and uint16 <-> int, which are useful in their own right.

There are many cast specializations now, some of which call each other.
I have tried to arrange them in some sort of sensible order, subject to
the constraint that those called must precede those who call.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1690633003
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review URL: https://codereview.chromium.org/1690633003

0 files changed, 0 insertions, 0 deletions