Reland "Fix sk_app macOS raster window build conditions."

The "raster" window on macOS and iOS is actually backed by GL. Fix the
build rules and code conditions to reflect this. This allows for some
sk_app applications to run on macOS and iOS with skia_use_gl=false.

> Revert:
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/397737
> Commit-Queue: Brian Osman <brianosman@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

> Land:
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/397256
> Commit-Queue: Ben Wagner <bungeman@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

Change-Id: Ia8a421f4818856dd90cb4847095eee0d1836d1e6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/398056
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
6 files changed