Fixes test_constraints, test_compile_to crashes in Halide built against llvm trunk
Fixes test_constraints, test_compile_to crashes in Halide built against llvm trunk


Former-commit-id: 8bfa4c29e1cc7a9eb37dc8507842abd56ec29810
Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide