Plug a memory leak.

If ibv_get_device_list() returns null, there's obviously no device list
to free, so we can just return - and, as ibv_free_device_list() is not
guaranteed to do nothing when passed a null pointer and, in fact, will
try to dereference the null pointer, we *must* return without calling
ibv_free_device_list().

However, if it returns a list, but there are no devices in the list, we
still have to free the list - the list is terminated with a null
pointer, so it's not empty.

The loop for adding devices from the list will terminate immediately if
numdev is 0, so don't bother to check whether it's zero, just run the
loop, which will do nothing if numdev is 0, and fall through to free the
device list.

While we're at it, replace a goto with a break that does the same thing.

pcap-rdmasniff.c

@@ -415,7 +415,7 @@ rdmasniff_findalldevs(pcap_if_list_t *devlistp, char *err_str)
 	int ret = 0;
 
 	dev_list = ibv_get_device_list(&numdev);
-	if (!dev_list || !numdev) {
+	if (!dev_list) {
 		return 0;
 	}
 
@@ -426,11 +426,10 @@ rdmasniff_findalldevs(pcap_if_list_t *devlistp, char *err_str)
 		 */
 		if (!add_dev(devlistp, dev_list[i]->name, 0, "RDMA sniffer", err_str)) {
 			ret = -1;
-			goto out;
+			break;
 		}
 	}
 
-out:
 	ibv_free_device_list(dev_list);
 	return ret;
 }