net: diag: support SOCK_DESTROY for UDP sockets

This implements SOCK_DESTROY for UDP sockets similar to what was done
for TCP with commit c1e64e298b8ca ("net: diag: Support destroying TCP
sockets.") A process with a UDP socket targeted for destroy is awakened
and recvmsg fails with ECONNABORTED.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 81e2f98..16512cf 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1467,6 +1467,7 @@
 	.compat_getsockopt = compat_udpv6_getsockopt,
 #endif
 	.clear_sk	   = udp_v6_clear_sk,
+	.diag_destroy      = udp_abort,
 };
 
 static struct inet_protosw udpv6_protosw = {