vnc: fix numlock+capslock tracking

This patch makes the numlock+capslock tracking logic only look at
keydown events.  Without this patch the vnc server will insert
bogous capslock keypress in case it sees the following key sequence:

  shift down --- 'A' down --- shift up  --- 'A' up
                                         ^ here

It doesn't hurt with a PS/2 keyboard, but it disturbs the USB Keyboard.
And with the key event queue just added to the usb keyboard the guest
will actually notice.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

ui/vnc.c

@@ -1504,7 +1504,7 @@ static void do_key_event(VncState *vs, int down, int keycode, int sym)
         break;
     }
 
-    if (vs->vd->lock_key_sync &&
+    if (down && vs->vd->lock_key_sync &&
         keycode_is_keypad(vs->vd->kbd_layout, keycode)) {
         /* If the numlock state needs to change then simulate an additional
            keypress before sending this one.  This will happen if the user
@@ -1523,7 +1523,7 @@ static void do_key_event(VncState *vs, int down, int keycode, int sym)
         }
     }
 
-    if (vs->vd->lock_key_sync &&
+    if (down && vs->vd->lock_key_sync &&
         ((sym >= 'A' && sym <= 'Z') || (sym >= 'a' && sym <= 'z'))) {
         /* If the capslock state needs to change then simulate an additional
            keypress before sending this one.  This will happen if the user