[LLD][COFF] Allow overriding EC alias symbols with lazy archive symbols (#113283)
On ARM64EC, external function calls emit a pair of weak-dependency
aliases: `func` to `#func` and `#func` to the `func` guess exit thunk
(instead of a single undefined `func` symbol, which would be emitted on
other targets). Allow such aliases to be overridden by lazy archive
symbols, just as we would for undefined symbols.