add android.fp16 build

The skcms-Linux bots should hit this new path,
and I can get it on my desktop too.

Change-Id: I22871af7dde1f2dd8102002811a117593d3d2e64
Reviewed-on: https://skia-review.googlesource.com/128921
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
4 files changed