progs/tests: compile with SCons and glew

Also get mingw cross-compilation of these tests working
diff --git a/progs/tests/random.c b/progs/tests/random.c
index d52c338..4023674 100644
--- a/progs/tests/random.c
+++ b/progs/tests/random.c
@@ -5,13 +5,13 @@
  * 21 June 2007
  */
 
-#define GL_GLEXT_PROTOTYPES
 
 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include <GL/glew.h>
 #include <GL/glut.h>
 
 static int Win;
@@ -445,6 +445,7 @@
    glutInitWindowSize(Width, Height);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    Win = glutCreateWindow(argv[0]);
+   glewInit();
    ParseArgs(argc, argv);
    glutReshapeFunc(Reshape);
    glutKeyboardFunc(Key);