allow #[rustc_align_static(N)] on statics

We need a different attribute than `rustc_align` because unstable attributes are
tied to their feature (we can't have two unstable features use the same
unstable attribute). Otherwise this uses all of the same infrastructure
as `#[rustc_align]`.

compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs

@@ -218,6 +218,7 @@ impl<S: Stage> AttributeParser<S> for NakedParser {
             sym::rustc_std_internal_symbol,
             // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
             sym::rustc_align,
+            sym::rustc_align_static,
             // obviously compatible with self
             sym::naked,
             // documentation