progs/demos: fix glut initialization calls

Remove glutInitWindowPosition() calls to play nicer with window managers.

Move glutInitWindowSize() calls before glutInit() so the the default window
size can be overridden by the -geometry cmd line option.
diff --git a/progs/demos/fbo_firecube.c b/progs/demos/fbo_firecube.c
index b3f7e00..17767a1 100644
--- a/progs/demos/fbo_firecube.c
+++ b/progs/demos/fbo_firecube.c
@@ -1051,11 +1051,11 @@
 int
 main(int argc, char *argv[])
 {
+   glutInitWindowSize(WinWidth, WinHeight);
    glutInit(&argc, argv);
 
    glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 
-   glutInitWindowSize(WinWidth, WinHeight);
    Win = glutCreateWindow("fbo_firecube");
    glewInit();
    init(argc, argv);