ipset: import ipset 5.2+GENL

This requires Linux 2.6.35 or newer to build, so it is deactivated by
default in the "mconfig" file.

extensions/ipset-5/Kbuild

@@ -0,0 +1,7 @@
+# -*- Makefile -*-
+
+obj-m += xt_set.o
+obj-m += ip_set.o ip_set_bitmap_ip.o ip_set_bitmap_ipmac.o
+obj-m += ip_set_bitmap_port.o ip_set_hash_ip.o ip_set_hash_ipport.o
+obj-m += ip_set_hash_ipportip.o ip_set_hash_ipportnet.o ip_set_hash_net.o
+obj-m += ip_set_hash_netport.o ip_set_list_set.o