Add support for SkImageRef_ashmem.

This requires copying the ashmem utility wrapper functions from a
private android library into our source tree in order to be NDK
compliant.

Review URL: https://codereview.appspot.com/6846076

git-svn-id: http://skia.googlecode.com/svn/trunk@6488 2bbb7eff-a529-9590-31e7-b0007b416f81
5 files changed