[lld] [LLD] [COFF] Warn if the runtime pseudo relocation function is missing (PR #88573)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

CC @mati865 @jeremyd2019 

What do others think - should we make this a hard error, or just a friendly warning? (This issue was brought up in https://github.com/llvm/llvm-project/issues/84424#issuecomment-2051898704.)

Ideally I'd like to make the linker try to pull in this function once we realize we need runtime pseudo relocs; I have a WIP patch for that since a long time, but I feel that it's a bit messy, and as long as ld.bfd isn't fixed to work in the same way, we can't really make use of it.

https://github.com/llvm/llvm-project/pull/88573