[lld] [LLD][COFF] Add support for MinGW auto-export on ARM64X (PR #125862)

[Jacek Caban via llvm-commits]

cjacek wrote:

The decision to handle explicit exports separately for each symbol table is somewhat arbitrary, but it provides more flexibility. If users prefer a different behavior, they can explicitly control auto-exports using command-line arguments.

(Handling ARM64X in MinGW is still undecided, but I’m sending these changes now to avoid inconsistencies caused by silently ignoring them.)

https://github.com/llvm/llvm-project/pull/125862