halide_metal_device_free() needs to clear buf->host
halide_metal_device_free() needs to clear buf->host

If buf->host is set here, it should be a pointer we obtained from the
mtl_buffer we’re releasing, and thus isn’t valid any more; generic code
in halide_device_and_host_free() will pass this pointer to
halide_free() if it’s not null, which will at best be useless, or at
worst, crater in amusing ways.


Former-commit-id: 5dc3bee82ca2c2117037cc8d5cab76d6cea6d59e
Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide