[clang] Unify the new covariant tests, remove T13 and add the new tests into T2 and T6.

In T2, we check that return types that are pointers to different non-class types fail.
In T6, we check that unlike class return types, non-class return types do not allow to change qualifiers at all (add or remove).

Author: bricknerb

clang/test/SemaCXX/virtual-override.cpp

@@ -19,10 +19,12 @@ struct b { };
 
 class A {
   virtual a* f(); // expected-note{{overridden virtual function is here}}
+  virtual int *g(); // expected-note{{overridden virtual function is here}}
 };
 
 class B : A {
   virtual b* f(); // expected-error{{return type of virtual function 'f' is not covariant with the return type of the function it overrides ('b *' is not derived from 'a *')}}
+  virtual char *g(); // expected-error{{virtual function 'g' has a different return type ('char *') than the function it overrides (which has return type 'int *')}}
 };
 
 }
@@ -83,11 +85,15 @@ struct a { };
 class A {
   virtual const a* f(); 
   virtual a* g(); // expected-note{{overridden virtual function is here}}
+  virtual const int* h(); // expected-note{{overridden virtual function is here}}
+  virtual int* i(); // expected-note{{overridden virtual function is here}}
 };
 
 class B : A {
   virtual a* f(); 
   virtual const a* g(); // expected-error{{return type of virtual function 'g' is not covariant with the return type of the function it overrides (class type 'const a *' is more qualified than class type 'a *'}}
+  virtual int* h();  // expected-error{{virtual function 'h' has a different return type ('int *') than the function it overrides (which has return type 'const int *')}}
+  virtual const int* i(); // expected-error{{virtual function 'i' has a different return type ('const int *') than the function it overrides (which has return type 'int *')}}
 };
 
 }
@@ -289,13 +295,3 @@ namespace PR8168 {
     static void foo() {} // expected-error{{'static' member function 'foo' overrides a virtual function}}
   };
 }
-
-namespace T13 {
-  struct A {
-    virtual const int *f() const; // expected-note{{overridden virtual function is here}}
-  };
-
-  struct B : A {
-    int *f() const override; // expected-error{{virtual function 'f' has a different return type ('int *') than the function it overrides (which has return type 'const int *')}}
-  };
-}