Rollup merge of #143599 - folkertdev:x86-asm-syntax-global-naked-asm, r=Amanieu

emit `.att_syntax` when global/naked asm use that option

fixes rust-lang/rust#143542

LLVM would error when using `-Cllvm-args=-x86-asm-syntax=intel` in combination with global/naked assembly with `att_syntax`. It turns out that for LLVM you do in this case need to emit `.att_syntax`.

r? `@Amanieu`

Author: matthiaskrgr