demos: add some fflushes for windows
diff --git a/progs/demos/gearbox.c b/progs/demos/gearbox.c
index 35bde04..2dcf32f 100644
--- a/progs/demos/gearbox.c
+++ b/progs/demos/gearbox.c
@@ -314,6 +314,7 @@
          GLfloat seconds = (t - T0) / 1000.0;
          GLfloat fps = Frames / seconds;
          printf("%d frames in %6.3f seconds = %6.3f FPS\n", Frames, seconds, fps);
+         fflush(stdout);
          T0 = t;
          Frames = 0;
       }