[clang] [Clang][AMDGPU][Driver] Add `avail-extern-gv-in-addrspace-to-local` option when ThinTLO is enabled (PR #144914)

[Shilei Tian via cfe-commits]

shiltian wrote:

> Bit of a hack it seems

It is a hack (or workaround). The correct approach would be either to redesign the lowering of LDS, or create another flavor of ThinLTO. Neither of it can be done in a reasonably short amount of time.

https://github.com/llvm/llvm-project/pull/144914