Ensure that SkMipMap pixel data is always 8 byte aligned (for F16)

Bug: skia:8410 chromium:876349
Change-Id: Ib97c82cd165f7e2f2e94c65fc307220b99053df3
Reviewed-on: https://skia-review.googlesource.com/c/174065
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
3 files changed