Make SkRuntimeEffect's compiler instance shareable.

No functional change.

Bug: skia:12720
Change-Id: I649bc258c9a6b4973cdd9d1727827cdaf89b43ad
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/481280
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
4 files changed