[PATCH] Fix NQ windows build

The NQ windows video driver also needs the IsFullScreen function.

diff -urN -X exclude a/NQ/vid_win.c head/NQ/vid_win.c
--- a/NQ/vid_win.c	2006-03-12 06:15:47.000000000 +1030
+++ head/NQ/vid_win.c	2006-06-11 09:16:10.000000000 +0930
@@ -3180,3 +3180,9 @@
 	break;
     }
 }
+
+qboolean
+VID_IsFullScreen()
+{
+    return VID_GetModePtr(vid_modenum)->fullscreen;
+}
