Reject unsupported naked functions

Transition unsupported naked functions future incompatibility lint into
an error:

* Naked functions must contain a single inline assembly block.
  Introduced as future incompatibility lint in 1.50 #79653.
  Change into an error fixes a soundness issue described in #32489.

* Naked functions must not use any forms of inline attribute.
  Introduced as future incompatibility lint in 1.56 #87652.

compiler/rustc_lint/src/lib.rs

@@ -481,6 +481,11 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
          <https://github.com/rust-lang/rust/issues/59014> for more information",
     );
     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
+    store.register_removed(
+        "unsupported_naked_functions",
+        "converted into hard error, see RFC 2972 \
+         <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {