Don't elide GrMatrixEffect if matrix is identity.
Don't elide GrMatrixEffect if matrix is identity.

This ensures an effect setup code path that calls GrMatrix::Make()
doesn't produce an identity and non-identity shader variant.

Change-Id: I4d17395ed1b5bfd2bf9ceac68e85756c18eb2d2f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/396018
Reviewed-by: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>
Commit-Queue: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>

google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia