Remove the debug crate's hard-coded dependency on register ordering

cranelift/codegen/src/isa/mod.rs

@@ -64,6 +64,7 @@ use crate::timing;
 use alloc::borrow::Cow;
 use alloc::boxed::Box;
 use core::fmt;
+use core::fmt::{Debug, Formatter};
 use target_lexicon::{triple, Architecture, PointerWidth, Triple};
 use thiserror::Error;
 
@@ -390,3 +391,14 @@ pub trait TargetIsa: fmt::Display + Send + Sync {
         // No-op by default
     }
 }
+
+impl Debug for &dyn TargetIsa {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "TargetIsa {{ triple: {:?}, pointer_width: {:?}}}",
+            self.triple(),
+            self.pointer_width()
+        )
+    }
+}