add --skvm to nanobench and fm

This might be easier than building with SK_USE_SKVM_BLITTER defined.

Change-Id: I72c1f361195bacf5a14e6633dd49e9a5ad721cff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264383
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
3 files changed