test (and fix?) SkVM JIT on arm64 Android bots

This has failed in the past on GPU perf bots,
I think because I've been flushing the cache wrong?

Try switching over to __builtin___clear_cache(), what I used
a few years ago when I last tried to do something like this.

Cq-Include-Trybots: skia.primary:Perf-Android-Clang-Nexus5x-GPU-Adreno418-arm64-Release-All-Android
Change-Id: Ic5e366022eb15f4544fb7b90a75f8c51e36392ca
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/227421
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
2 files changed