[graphite] Patch up some Vulkan shader issues

* The validator is complaining when we tear down the device that there
are shader modules still around, so clean up the shader modules that
don't get used yet to make a pipeline.
* At least one shader is failing to compile and we hadn't set up an

Bug: b/277583609
Change-Id: I4c9f19aaed64c6ce596a127d0cfe5935efda67a0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/702840
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
2 files changed