Remove all usage of libm / math.h

Change-Id: I959768573ebed547d747b4c0d6d089db29278ffd
Reviewed-on: https://skia-review.googlesource.com/118760
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@google.com>
18 files changed