Don't force GrGLSLVarying's scope to be compile-time constant

Bug: skia:
Change-Id: I70a191949fd26a39257a8a59a0a4c6448ec1fa37
Reviewed-on: https://skia-review.googlesource.com/82462
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
20 files changed