a93eb14e85
Add new APIs to legacy LTO C API to surface undefined symbols that parsed from assembly. This information is needed by thin LTO to figure out the symbols not to dead strip, while such information is automatically forwarded in full LTO already. Linker needs to fetch the information and adds the undefs from assembly to MustPreserveSymbols list just like treating undefs from a non-LTO object file. Resolves: https://github.com/llvm/llvm-project/issues/29340