forward: Make sure pip flags are treated as unsigned

forward: Make sure pip flags are treated as unsigned

process_ip_header already expects them to be unsigned,
make sure the flags are to avoid spurious conversion warnings.

Change-Id: I6d42c67b8dc5512933bed482bd9c2be80c63e993
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20250901194531.13683-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg32740.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>