[clang] [Clang/AMDGPU] Allow zero sized arrays in HIP device code (PR #195716)

[Shilei Tian via cfe-commits]

shiltian wrote:

> > A zero-size dynamic LDS can also mean just alias of the dynamic LDS buffer and they can just get the same address?
> 
> 0 sized objects are supposed to all get the same address

Right, so this should be allowed.

https://github.com/llvm/llvm-project/pull/195716