Add default ctor to Halide::Type
Add default ctor to Halide::Type

(I haven’t actually found instances of using any uninitialized
instances; this is a pre-emptive strike.)


Former-commit-id: 9d5a41ce99961335d746ca3e82840cd219c6dcdf
Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide