Update SkiaSDLExample to latest Ganesh interfaces.

Also updates SDL to 2.0.5.

Change-Id: I3a3c8f69360fc20a3d543c19dcf82dd3f42f1309
Reviewed-on: https://skia-review.googlesource.com/22204
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
4 files changed