Fix warnings

modules/video_output/msw/events.c

@@ -98,7 +98,7 @@ void* EventThread( vlc_object_t *p_this )
     MSG msg;
     POINT old_mouse_pos = {0,0}, mouse_pos;
     vlc_value_t val;
-    int i_width, i_height, i_x, i_y;
+    unsigned int i_width, i_height, i_x, i_y;
     HMODULE hkernel32;
 
     /* Initialisation */

modules/video_output/msw/wingdi.c

@@ -635,6 +635,8 @@ static int Manage( vout_thread_t *p_vout )
 static void Render( vout_thread_t *p_vout, picture_t *p_pic )
 {
     /* No need to do anything, the fake direct buffers stay as they are */
+    (void)p_vout;
+    (void)p_pic;
 }
 
 /*****************************************************************************