netstat-nat: add license information

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/netstat-nat/netstat-nat.mk

@@ -6,5 +6,7 @@
 
 NETSTAT_NAT_VERSION = 1.4.10
 NETSTAT_NAT_SITE = http://tweegy.nl/download
+NETSTAT_NAT_LICENSE = GPLv2+
+NETSTAT_NAT_LICENSE_FILES = COPYING
 
 $(eval $(autotools-package))