Add iOS support for SkiaSDLExample.

Change-Id: Ib8f4d6c41356cf0fe2e14b7bff7713d107eaa01f
Reviewed-on: https://skia-review.googlesource.com/40687
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
4 files changed