Rename define_function to define_function_with_control_plane (#6165)

And add a define_function convenience function which uses a default
control plane.

cranelift/jit/examples/jit-minimal.rs

@@ -51,10 +51,7 @@ fn main() {
         bcx.seal_all_blocks();
         bcx.finalize();
     }
-    let ctrl_plane = &mut Default::default();
-    module
-        .define_function(func_a, &mut ctx, ctrl_plane)
-        .unwrap();
+    module.define_function(func_a, &mut ctx).unwrap();
     module.clear_context(&mut ctx);
 
     ctx.func.signature = sig_b;
@@ -77,9 +74,7 @@ fn main() {
         bcx.seal_all_blocks();
         bcx.finalize();
     }
-    module
-        .define_function(func_b, &mut ctx, ctrl_plane)
-        .unwrap();
+    module.define_function(func_b, &mut ctx).unwrap();
     module.clear_context(&mut ctx);
 
     // Perform linking.