Add simple subclass tests

Author: bzoracler

test-data/unit/check-deprecated.test

@@ -326,15 +326,21 @@ class C:
     @classmethod
     def make_c(cls) -> C: ...
 
+class C2(C): ...
+
 C()  # E: function __main__.C.__init__ is deprecated: call `make_c()` instead
+C2()  # E: function.__main__.C.__init__ is deprecated: call `make_c()` instead
 
 class D:
     @deprecated("call `make_d()` instead")
     def __new__(cls) -> D: ...
     @classmethod
     def make_d(cls) -> D: ...
 
+class D2(D): ...
+
 D()  # E: function __main__.D.__new__ is deprecated: call `make_d()` instead
+D2()  # E: function __main__.D.__new__ is deprecated: call `make_d()` instead
 
 [builtins fixtures/tuple.pyi]