[lld] [LLD][COFF] Add support for locally imported EC symbols (PR #114985)

[Jacek Caban via llvm-commits]

cjacek wrote:

Locally imported symbols are problematic on ARM64EC due to the existence of both `__imp_` and `__imp_aux_` symbols, which provide different guarantees. For example, if we aim to match actual imports, and the symbol is defined as an x86_64 function, the __imp_ symbol would need to use a generated thunk, but only when referenced from ARM64EC code. MSVC does not seem to support this behavior, and I have followed that pattern here. This approach should be sufficient for most cases and allows for emitting a proper warning.


https://github.com/llvm/llvm-project/pull/114985