xfree86 DDX: Delete DDX screens in ddxGiveUp().

This allows video drivers to clean up in the FreeScreen hook things they set up
in the PreInit hook.

hw/xfree86/common/xf86Init.c

@@ -1119,6 +1119,9 @@ ddxGiveUp()
     DGAShutdown();
 #endif
 
+    while (xf86NumScreens)
+	xf86DeleteScreen(xf86NumScreens - 1, 0);
+
     xf86CloseConsole();
 
     xf86CloseLog();