multi-socket: do not return tuntap flags on server-side

multi-socket: do not return tuntap flags on server-side

Tuntap flags are already handled within
multi_io_process_io() so return them by
multi_io_process_flags() would be redoundant,
since we need them only for tun_set().

While at it, removed part of the I/O process
from multi_process_io_udp() since those are
also handled within multi_io_process_io(),
removed the FILE_CLOSED and FILE_SHIFT
defines since we now handle that kind of
event in multi_io_process_io() through
the MULTI_IO_FILE_CLOSE_WRITE define.

Change-Id: I6a5110a0583b8b33496b06d9c27c1084df38e842
Signed-off-by: Gianmarco De Gregori <gianmarco@mandelbit.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1364
Message-Id: <20251124175832.21352-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg34650.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>