Silence warnings about using offsetof on near-POD structs.

This is coming up with SkMatrix, which is POD according to GCC >= 4.6
but not before (specifically, not at GCC 4.4).

BUG=skia:
R=reed@google.com, mtklein@google.com, bungeman@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/339193002
1 file changed