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

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

ab7be415ab419c2c94adc560b4a05ef6dba27642 looks conservatively correct.  Sure, just merging that to main and 18 for now seems like a plan.

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