[llvm] [aarch64][win] Add support for import call optimization (equivalent to MSVC /d2ImportCallOptimization) (PR #121516)

[Daniel Paoliello via llvm-commits]

dpaoliello wrote:

> Yes, a relocation (at the assembler level, not in the resulting object). We have infrastructure to do this if you wanted to.

Sure, can you point me to the code?

I'd be happy to get rid of the `.impcall` directive and do most of the work in the asm printer, as it'll make the x86 implementation easier.

https://github.com/llvm/llvm-project/pull/121516