[lld] [lld] Merge equivalent symbols found during ICF (PR #134342)

[Hans Wennborg via llvm-commits]

zmodem wrote:

Our problem seems related to the `'__typeid_..._{bit,byte,unique_member}` symbols inserted by WholeProgramDevirt.cpp. If I exclude those from "redirecting", it appears to fix the tests.

That Fuchsia uses -fexperimental-relative-c++-abi-vtables may or may not explain why we only see it there.

https://github.com/llvm/llvm-project/pull/134342