explorer: Zero initialize DEVMODE before passing it to EnumDisplaySettings().

EnumDisplaySettings() on Wine does not write beyond the end of DEVMODE because it doesn't use
dmDriverExtra currently, but this implementation detail should not be relied on.

Signed-off-by: Zhiyi Zhang <zzhang@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

programs/explorer/desktop.c

@@ -889,6 +889,7 @@ static void initialize_display_settings(void)
 
     /* Store current display mode in the registry */
     ddW.cb = sizeof(ddW);
+    memset(&dmW, 0, sizeof(dmW));
     dmW.dmSize = sizeof(dmW);
     while (EnumDisplayDevicesW( NULL, i++, &ddW, 0 ))
     {