ipv4: Fix erroneous uses of ifa_address.

In usual cases ifa_address == ifa_local, but in the case where
SIOCSIFDSTADDR sets the destination address on a point-to-point
link, ifa_address gets set to that destination address.

Therefore we should use ifa_local when we want the local interface
address.

There were two cases where the selection was done incorrectly:

1) When devinet_ioctl() does matching, it checks ifa_address even
   though gifconf correct reported ifa_local to the user

2) IN_DEV_ARP_NOTIFY handling sends a gratuitous ARP using
   ifa_address instead of ifa_local.
Reported-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/devinet.c

@@ -670,7 +670,7 @@ int devinet_ioctl(struct net *net, unsigned int cmd, void __user *arg)
 			     ifap = &ifa->ifa_next) {
 				if (!strcmp(ifr.ifr_name, ifa->ifa_label) &&
 				    sin_orig.sin_addr.s_addr ==
-							ifa->ifa_address) {
+							ifa->ifa_local) {
 					break; /* found */
 				}
 			}
@@ -1040,8 +1040,8 @@ static void inetdev_send_gratuitous_arp(struct net_device *dev,
 		return;
 
 	arp_send(ARPOP_REQUEST, ETH_P_ARP,
-		 ifa->ifa_address, dev,
-		 ifa->ifa_address, NULL,
+		 ifa->ifa_local, dev,
+		 ifa->ifa_local, NULL,
 		 dev->dev_addr, NULL);
 }