Complete JITLink ELF/AArch64 backend.

[lhames]

Bugzilla Link	51924
Version	trunk
OS	All
CC	@AlexDenisov,@lhames,@weliveindetail

Extended Description

Once we have a fully working ELF/AArch64 backend for JITLink we can use it rather than RuntimeDyld. This will help us to fix https://bugs.swift.org/browse/SR-15213 (though slab memory allocation may still be required for that bug).

[sunho]

We can close this now. ELF/AARCH64 is complete enough to be usable in julia. (JuliaLang/julia#45859)

[llvmbot]

@llvm/issue-subscribers-backend-aarch64