Fixed bug in schedule_transforms
Fixed bug in schedule_transforms

Schedule transforms no longer allows chunking across variables that are not in scope for some uses of the function in question.

Former-commit-id: c323ff7d0177abd71f9af2ca90428e2e35fee483
darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide