Rollup merge of rust-lang#130146 - folkertdev:bootstrap-naked-asm, r=…

…Amanieu

bootstrap `naked_asm!` for `compiler-builtins`

tracking issue: rust-lang#90957
parent PR: rust-lang#128651

in this PR, `naked_asm!` is added as an alias for `asm!` with one difference: `options(noreturn)` is always enabled by `naked_asm!`. That makes it future-compatible for when `naked_asm!` starts disallowing `options(noreturn)` later.

The `naked_asm!` macro must be introduced first so that we can upgrade `compiler-builtins` to use it, and can then change the implementation of `naked_asm!` in rust-lang#128651

I've added some usages for `naked_asm!` in the tests, so we can be confident that it works, but I've left upgrading the whole test suite to the parent PR.

r? ``@Amanieu``

core/src/arch.rs

@@ -17,6 +17,20 @@ pub macro asm("assembly template", $(operands,)* $(options($(option),*))?) {
     /* compiler built-in */
 }
 
+/// Inline assembly used in combination with `#[naked]` functions.
+///
+/// Refer to [Rust By Example] for a usage guide and the [reference] for
+/// detailed information about the syntax and available options.
+///
+/// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
+/// [reference]: https://doc.rust-lang.org/nightly/reference/inline-assembly.html
+#[unstable(feature = "naked_functions", issue = "90957")]
+#[rustc_builtin_macro]
+#[cfg(not(bootstrap))]
+pub macro naked_asm("assembly template", $(operands,)* $(options($(option),*))?) {
+    /* compiler built-in */
+}
+
 /// Module-level inline assembly.
 ///
 /// Refer to [Rust By Example] for a usage guide and the [reference] for