Compile in namespaced builds

Change-Id: I2894fbadec50286c0831bf381d149b54ade9182d
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

examples/opengl/hellogles3/glwindow.h

@@ -46,11 +46,15 @@
 #include <QVector3D>
 #include "../hellogl2/logo.h"
 
+QT_BEGIN_NAMESPACE
+
 class QOpenGLTexture;
 class QOpenGLShaderProgram;
 class QOpenGLBuffer;
 class QOpenGLVertexArrayObject;
 
+QT_END_NAMESPACE
+
 class GLWindow : public QOpenGLWindow
 {
     Q_OBJECT