progs/tests: compile with SCons and glew

Also get mingw cross-compilation of these tests working

progs/tests/arraytexture.c

@@ -34,6 +34,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <math.h>
+#include <GL/glew.h>
 #include <GL/glut.h>
 #include <GL/glext.h>
 
@@ -326,6 +327,7 @@ int main(int argc, char *argv[])
    glutInitWindowSize(350, 350);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
    glutCreateWindow("Array texture test");
+   glewInit();
    glutReshapeFunc(Reshape);
    glutKeyboardFunc(Key);
    glutSpecialFunc(SpecialKey);