GCC 4.6 compatibility: no `override` keyword.

src/Shapes/shapeImplementation.h

@@ -26,6 +26,7 @@
 
 #include <utility>
 #include <Utility/Assert.h>
+#include <corradeCompatibility.h>
 
 #include "DimensionTraits.h"
 #include "Magnum.h"

src/Test/AbstractOpenGLTester.h

@@ -25,6 +25,7 @@
 */
 
 #include <TestSuite/Tester.h>
+#include <corradeCompatibility.h>
 
 #include "Renderer.h"