progs/trivial: Use glew where needed.

Builds on windows now.
diff --git a/progs/trivial/drawarrays.c b/progs/trivial/drawarrays.c
index 596eee9..27d8668 100644
--- a/progs/trivial/drawarrays.c
+++ b/progs/trivial/drawarrays.c
@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
-#define GL_GLEXT_PROTOTYPES
+#include <GL/glew.h>
 #include <GL/glut.h>
 
 
@@ -118,6 +118,7 @@
    glutInitWindowSize( 250, 250 );
    glutInitDisplayMode( GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH );
    glutCreateWindow(argv[0]);
+   glewInit();
    glutReshapeFunc( Reshape );
    glutKeyboardFunc( Key );
    glutDisplayFunc( Display );