Spin off just SkLazyFnPtr from 305513002.

The memory barrier in SkOnce is a perf regression for sk_mem{set,cpy} in
SkUtils on ARM.  We can do a lot better for function pointers.

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

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/305753002

git-svn-id: http://skia.googlecode.com/svn/trunk@14929 2bbb7eff-a529-9590-31e7-b0007b416f81
5 files changed