SkVM implement min max

Change-Id: I225e8f7395e58a4ca3c1c151d8711796e6a56939
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/274185
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2 files changed