[lld] [lld][NFC] Silence -Wuninitialized GCC warnings. (PR #75183)

[Jacek Caban via llvm-commits]

cjacek wrote:

I found that we already disable -Wmaybe-uninitialized. I created #76251 which disables all -Wuninitialized for GCCs older than 11. We could potentially try to utilize CHECK_C_SOURCE_COMPILES, but for cases like this, it's tricky to find reliable and simple enough tests case. I ended up using a compiler version check, but we could easily change it to be unconditional if that's preferred (that would mean that for some developers warnings would be unnoticed before pushing, through).

If/when #76251 lands, I will revert this PR.

https://github.com/llvm/llvm-project/pull/75183