Fixed error on some compilers regarding comparison of signed/unsigned in cast tests.
Fixed error on some compilers regarding comparison of signed/unsigned in cast tests.


Former-commit-id: 052cd1066723aceee72264268fc86ad6025df509
darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide