[llvm] [GlobalOpt] Don't replace aliasee with alias that has weak linkage (PR #91483)

[via llvm-commits]

DianQK wrote:

> I'm having trouble following all the different cases interleaved together. I just spent half an hour trying to follow this, and I feel like I understand less than when I started.
> 
> Please delete the `Ret` variable, and replace the corresponding logic with something actually comprehensible.

How do you feel about this PR only being submitted as ab7be415ab419c2c94adc560b4a05ef6dba27642? I want to *backport it to LLVM 18*. I can create another PR for b901a982d8e618d13049e5a804d19bce30fbac3c. 




https://github.com/llvm/llvm-project/pull/91483