[llvm] [MergeFunc] Remove discardables function before writing alias or thunk. (PR #128865)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

I updated the tests manually for now, will see if I can put up a patch for the update script separately, thanks!

https://github.com/llvm/llvm-project/pull/128865