Non-substantive Vulkan backend changes

These changes just serve to muddy the water in the real CL.

This is pulled out of:
https://skia-review.googlesource.com/c/skia/+/288462 ([Omnibus] Add program pre-compilation to Vulkan backend)

Change-Id: I033ff7976ce0ee39e9e99b6dec1b80277f7c04ab
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/289221
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
7 files changed