[clang] [clang][CodeGen] Skip deleted globals in emitUsed (PR #210959)

[Vassil Vassilev via cfe-commits]

vgvassilev wrote:

> @vgvassilev @efriedma-quic this is approved and CI is green is there anything else we need on this one before it can land? Thanks!

Aaron added @asl afterwards and I wanted to give him a chance to look. Let's wait for another week and we can land it...

https://github.com/llvm/llvm-project/pull/210959