Revert "Revert "Disable F16-nullptr sources""

This relands the original change with a modification.  We should
not check for non-null pixels because this breaks the Android
hw bitmap use case.

Bug: b/62482405
Change-Id: I081412bb46754d33b69e02e5754f04a082e081ae
Reviewed-on: https://skia-review.googlesource.com/19494
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
4 files changed