Improve SPIR-V handling of RTFlip when running the fuzzer.

If the passed-in shader references RTFlip (i.e., sk_FragCoord is used),
the settings must contain RTFlip layout info; otherwise, an error
occurs. Originally, the fuzzer detected this as a problem because the
error was being delivered via SK_ABORT, but it's failing more cleanly
now that Ethan's new error handling code is in place (causing the fuzzer
to report that the bug was "fixed"). With this CL, the oss-fuzz shader
will actually compile successfully in SPIR-V instead of leading to an
error.

Change-Id: I3268e84bd8e01c95a25ed0845a37324e98033c4b
Bug: oss-fuzz:35916
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/439779
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
4 files changed