[llvm] [Offload] Allow setting null arguments in olLaunchKernel and fix amdgpu handling for empty kernel arguments (PR #141958)

[Joseph Huber via llvm-commits]

https://github.com/jhuber6 commented:

I'm going to make a separate fix for the AMDGPU stuff. `free(malloc(0))` is explicitly defined by the standard to work so that is what we should do. If the size is zero a nullptr argument is perfectly valid.

https://github.com/llvm/llvm-project/pull/141958