Add ARM optimizations to the build.

Also had to fix a problem in the ARM memset code that was
causing some tests and bench to fail.
Review URL: http://codereview.appspot.com/5522052

git-svn-id: http://skia.googlecode.com/svn/trunk@2989 2bbb7eff-a529-9590-31e7-b0007b416f81
5 files changed