ipv4: enable getsockopt() for IP_NODEFRAG

While integrating your man-pages patch for IP_NODEFRAG, I noticed
that this option is settable by setsockopt(), but not gettable by
getsockopt(). I suppose this is not intended. The (untested,
trivial) patch below adds getsockopt() support.

Signed-off-by: Michael kerrisk <mtk.manpages@gmail.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_sockglue.c

@@ -1129,6 +1129,9 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
 	case IP_HDRINCL:
 		val = inet->hdrincl;
 		break;
+	case IP_NODEFRAG:
+		val = inet->nodefrag;
+		break;
 	case IP_MTU_DISCOVER:
 		val = inet->pmtudisc;
 		break;