[lld] [lld][ICF] Prevent merging two sections when they point to non-globals (PR #136641)

[Pranav Kant via llvm-commits]

pranavk wrote:

What are your thoughts on making this target specific in ICF as Peter mentioned? Just before ICF is about to merge two sections together, it makes a call to target specific virtual function that tells if it's permissible to merge two sections together. That keeps complexity out of linker's ICF algorithm and each target may or may not implement such a virtual function.

https://github.com/llvm/llvm-project/pull/136641