Hopefully fix windows build
Hopefully fix windows build

VarOrVar needs an operator= now, apparently


Former-commit-id: 6a1dc0d43d6e338c1f70bbd2ef98363a8f8d3488
darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide