Add missing intrinsic tests for abs/max/min(genIType), clamp(genType)

GPUs that failed continued to fail when I put in error bars like
`distance(a, b) <= 0.001`, so they're just disabled entirely now.
Presumably their results are very busted.

Change-Id: I0f1b80f661563a20630740f8cfb6ef69f2a47934
Bug: skia:11209, skia:12858
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/503817
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
7 files changed