Case for Xcoff not handled in `prefix_and_suffix`

[Pyr0de]

          Added Xcoff here with Elf since it wasn't taken into account before and AsmBinaryFormat defaulted to elf

Originally posted by @Pyr0de in #136637 (comment)

There is no case handling xcoff here and so it defaults to elf

[Pyr0de]

@rustbot label +O-aix

[folkertdev]

inline/global assembly for these targets does not appear to be well-supported in llvm. Many of the directives that LLVM itself emits are not supported by its assembly parser.

I've made this https://godbolt.org/z/xTq8rW876 which shows some of the issues (it needs a bunch of hackery so that we can actually compile for the target). So, I'm not sure that we can make much progress on the rust side without more LLVM support.

@rustbot label +F-naked-functions

[folkertdev]

@rustbot label +F-naked_functions +A-naked +A-inline-assembly