[mypyc] Use per-type free "lists" for nested functions

mypyc/irbuild/callable_class.py

@@ -56,6 +56,7 @@ class for the nested function.
     # environment to point at the previously defined environment
     # class.
     callable_class_ir = ClassIR(name, builder.module_name, is_generated=True, is_final_class=True)
+    callable_class_ir.reuse_freed_instance = True
 
     # The functools @wraps decorator attempts to call setattr on
     # nested functions, so we create a dict for these nested

mypyc/irbuild/env_class.py

@@ -48,6 +48,7 @@ class is generated, the function environment has not yet been
         is_generated=True,
         is_final_class=True,
     )
+    env_class.reuse_freed_instance = True
     env_class.attributes[SELF_NAME] = RInstance(env_class)
     if builder.fn_info.is_nested:
         # If the function is nested, its environment class must contain an environment