Merge fcdf440964 into 1c789726cf

Handle attribute NFTNL_SET_DESC_SIZE, as done in libnftnl:
https://git.netfilter.org/libnftnl/tree/src/set.c#n424

Example:
nft add set ip filter myset { type ipv4_addr\; size 65535\; flags dynamic\; }

set_test.go

@@ -237,7 +237,7 @@ func TestMarshalSet(t *testing.T) {
 				Size:       10,
 				Table:      tbl,
 				KeyType:    TypeIPAddr,
-				Timeout:    time.Duration(30) * time.Second,
+				Timeout:    30 * time.Second,
 			},
 		},
 	}