Fix a problem where pipsecd opens a tun device that was previously used
by another application that had the IFHEAD flag set. This fixes
truncation of incoming and outgoing packets because pipsecd expects this
flags to be cleared.

The MAINTAINER of this port (Patrick Bihan-Faou <patrick@mindstep.com>)
has asked to be removed as the maintainer of the port. As I still use
this port, I am adopting it as it's new MAINTAINER.

PR: ports/24753
Submitted by: quinot@inf.enst.fr