ipv4: Add a socket release callback for datagram sockets

ipv4: Add a socket release callback for datagram sockets

[ Upstream commit 8141ed9fcedb278f4a3a78680591bef1e55f75fb ]

This implements a socket release callback function to check
if the socket cached route got invalid during the time
we owned the socket. The function is used from udp, raw
and ping sockets.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>