SkSL: Hide non-square matrices from runtime effects

These don't exist in our minimum spec (GLSL ES 1.0)

Bug: skia:11093
Change-Id: Ia2d871199fff2a98dcd517c1eebe46decb0c2dfb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/346657
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
2 files changed