Add support for SkASSERTF and SkDEBUGFAIL(F) in SKSL_STANDALONE.

This is a simple safeguard to prevent against code that compiles
properly in full Skia builds, but fails in a SkSL standalone build.

A few SkASSERT(false) calls have been replaced with
SkDEBUGFAIL("message") in order to exercise the new call.

This CL should unblock
https://skia-review.googlesource.com/c/skia/+/292689

Change-Id: I83b0b9d28bd74c5cb1869510b0fb34792c6b2385
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/292693
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2 files changed