VS12: Remove duplicated overload of UseFolderProperty()

cmGlobalVisualStudio11Generator generator already defines the same
function body, which makes the additional overload useless.

Source/cmGlobalVisualStudio12Generator.cxx

@@ -100,12 +100,3 @@ cmLocalGenerator *cmGlobalVisualStudio12Generator::CreateLocalGenerator()
   lg->SetGlobalGenerator(this);
   return lg;
 }
-
-//----------------------------------------------------------------------------
-bool cmGlobalVisualStudio12Generator::UseFolderProperty()
-{
-  // Intentionally skip over the parent class implementation and call the
-  // grand-parent class's implementation. Folders are not supported by the
-  // Express editions in VS10 and earlier, but they are in VS12 Express.
-  return cmGlobalVisualStudio8Generator::UseFolderProperty();
-}

Source/cmGlobalVisualStudio12Generator.h

@@ -33,7 +33,6 @@ public:
   virtual std::string GetUserMacrosDirectory() { return ""; }
 protected:
   virtual const char* GetIDEVersion() { return "12.0"; }
-  bool UseFolderProperty();
 private:
   class Factory;
 };