Fix T69582: Empties no longer support Rigid Body Constraints

This is caused by rB1342d1879e12 and would also break the whole
"Connect" workflow [which relies on empties]

Reviewers: mont29, brecht

Maniphest Tasks: T69582

Differential Revision: https://developer.blender.org/D5772

source/blender/editors/physics/rigidbody_constraint.c

@@ -81,14 +81,7 @@ static bool ED_operator_rigidbody_con_add_poll(bContext *C)
        ID_IS_LINKED(&scene->rigidbody_world->constraints->id))) {
     return false;
   }
-
-  if (ED_operator_object_active_editable(C)) {
-    Object *ob = ED_object_active_context(C);
-    return (ob && ob->type == OB_MESH);
-  }
-  else {
-    return false;
-  }
+  return ED_operator_object_active_editable(C);
 }
 
 bool ED_rigidbody_constraint_add(