[X25]: Fix for broken x25 module.

When a user-space server application calls bind on a socket, then in kernel
space this bound socket is considered 'x25-linked' and the SOCK_ZAPPED flag
is unset.(As in x25_bind()/af_x25.c).

Now when a user-space client application attempts to connect to the server
on the listening socket, if the kernel accepts this in-coming call, then it
returns a new socket to userland and attempts to reply to the caller.

The reply/x25_sendmsg() will fail, because the new socket created on
call-accept has its SOCK_ZAPPED flag set by x25_make_new().
(sock_init_data() called by x25_alloc_socket() called by x25_make_new()
sets the flag to SOCK_ZAPPED)).

Fix: Using the sock_copy_flag() routine available in sock.h fixes this.

Tested on 32 and 64 bit kernels with x25 over tcp.

Signed-off-by: Shaun Pereira <pereira.shaun@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>