move conditions for JIT into SkVM.h

This makes it easier to keep in sync with the implementation in
SkVM.cpp, and it's easier to handle here once than in each build system.

Change-Id: I429f90cfc16f35a0d7e0b0fde176bc013aa7db18
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/310263
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Herb Derby <herb@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
3 files changed