[clang] [ClangLinkerWrapper] Forward --allow-multiple-definition to linker. (PR #182282)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 commented:

Also, is the issue the fact that we always extract for `.a` files? I've thought about ways to solve that. Either we obtain a symbol list from the user's input `.a`'s or we make dummy symbols in the host code.

https://github.com/llvm/llvm-project/pull/182282