various fixes for naked_asm! implementation

- fix for divergence
- fix error message
- fix another cranelift test
- fix some cranelift things
- don't set the NORETURN option for naked asm
- fix use of naked_asm! in doc comment
- fix use of naked_asm! in run-make test
- use `span_bug` in unreachable branch

src/tools/rustfmt/src/parse/macros/asm.rs

@@ -1,5 +1,5 @@
 use rustc_ast::ast;
-use rustc_builtin_macros::asm::{parse_asm_args, AsmArgs};
+use rustc_builtin_macros::asm::{AsmArgs, parse_asm_args};
 
 use crate::rewrite::RewriteContext;