Fix bug in memoize
Fix bug in memoize

Don't set a pointer to shape storage and then immediately clobber it


Former-commit-id: 77fcc7102a323e8d793f2e6e95664cf80fc8485d
darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide