Switch back to stack-based SkSL interpreter

It's slower, but code size is quite a bit smaller, memory usage is
smaller, and we think that mapping it to SkVM is just as easy.

This effectively reverts all of the following commits:

"Fix gcc9 warning around size of memset."
https://skia-review.googlesource.com/c/skia/+/279861

"Remove unused (and misleading) 'instruction' from SkSLInterpreter.h"
https://skia-review.googlesource.com/c/skia/+/278177

"Interpreter: Fix intrinsics when called with vector types"
https://skia-review.googlesource.com/c/skia/+/272721

"Make it easier to add vector versions of byte code instructions"
https://skia-review.googlesource.com/c/skia/+/272527

"Interpreter: Support returns from runStriped"
https://skia-review.googlesource.com/c/skia/+/268941

"add SkSLInterpreter vector instructions"
https://skia-review.googlesource.com/c/skia/+/266560

"Fix crash when editing particle scripts"
https://skia-review.googlesource.com/c/skia/+/269487

"Revert "Revert "Complete rewrite of the SkSL interpreter"""
https://skia-review.googlesource.com/c/skia/+/266205

Change-Id: I4258596399c4ca94489d4faf8aacfec88afeee13
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/281205
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
22 files changed