Fix a number of issues with iOS build.

Set pointer to root view in window (for SampleApp)
Set up the correct function pointer for GL multisampling
Remove use of SkBitmap::setConfig()
Remove incomplete iOS implementation of SkFILE (use SkOSFile for now)

R=caryclark@google.com, reed@google.com, bsalomon@google.com, tfarina@chromium.org

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/322403007
5 files changed