Correct for changed Qt opengl includes.
Reference: http://www.kdenlive.org/mantis/view.php?id=2396

diff -Naur kdenlive-0.8.2.1.orig//src/videoglwidget.cpp kdenlive-0.8.2.1/src/videoglwidget.cpp
--- kdenlive-0.8.2.1.orig//src/videoglwidget.cpp	2012-01-24 00:04:53.588121469 -0430
+++ kdenlive-0.8.2.1/src/videoglwidget.cpp	2012-01-24 00:05:32.817410938 -0430
@@ -2,6 +2,7 @@
 #include <QtGui>
 #include <QtOpenGL>
 #include "videoglwidget.h"
+#include "GL/glu.h"
 
 #ifndef GL_TEXTURE_RECTANGLE_EXT
 #define GL_TEXTURE_RECTANGLE_EXT GL_TEXTURE_RECTANGLE_NV