Generator::natural_vector_size() wraps Target::natural_vector_size()
Generator::natural_vector_size() wraps Target::natural_vector_size()

Former-commit-id: 3c768d94ace86c466a96e6dcbd82a03190c16ca2
darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide