Shaders: fix the non-deprecated ES2 build.

The initializer list is needed for Phong lights as well, not just (ES3+
only) skinning stuff.

src/Magnum/Shaders/PhongGL.h

@@ -32,6 +32,7 @@
  * @m_since_latest
  */
 
+#include <initializer_list>
 #include <Corrade/Utility/Move.h>
 
 #include "Magnum/GL/AbstractShaderProgram.h"
@@ -39,10 +40,6 @@
 #include "Magnum/Shaders/glShaderWrapper.h"
 #include "Magnum/Shaders/visibility.h"
 
-#ifndef MAGNUM_TARGET_GLES2
-#include <initializer_list>
-#endif
-
 namespace Magnum { namespace Shaders {
 
 /**