progs/tests: compile with SCons and glew

Also get mingw cross-compilation of these tests working
diff --git a/progs/tests/mapbufrange.c b/progs/tests/mapbufrange.c
index 04d57b5..0021bb2 100644
--- a/progs/tests/mapbufrange.c
+++ b/progs/tests/mapbufrange.c
@@ -9,13 +9,13 @@
  */
 
 
-#define GL_GLEXT_PROTOTYPES
 #include <assert.h>
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <GL/glew.h>
+#include <GL/glew.h>
 #include <GL/glut.h>
 
 static GLuint Win;
@@ -194,6 +194,7 @@
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
    Win = glutCreateWindow(argv[0]);
    glewInit();
+   glewInit();
    glutReshapeFunc(Reshape);
    glutKeyboardFunc(Key);
    glutDisplayFunc(Display);