Set NSError on compilation/link timeouts.

When compilation fails GrCompileMtlShaderLibrary expects the error
result to be set. This also allows us to print out all errors with
compilation and pipeline creation in central locations.

Change-Id: I7c3d5dda5bd46a95b55365cb0b8f07d79c030db6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/268625
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
2 files changed