[lld] [LLD][COFF] Use EC load config for ARM64X relocations of load config directory (PR #121337)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo approved this pull request.

LGTM, modulo the `int64_t` vs `uint64_t` detail.

(Sorry for losing track of this PR - feel free to ping me sooner if it looks like I've missed some PR.)

https://github.com/llvm/llvm-project/pull/121337