Drop -W from CFLAGS and some tiny code cleanups

- change "unsigned" to explicit "unsigned int"
- remove some casts
diff --git a/extensions/libip6t_rt.c b/extensions/libip6t_rt.c
index a9ced6a..e2ae09f 100644
--- a/extensions/libip6t_rt.c
+++ b/extensions/libip6t_rt.c
@@ -255,7 +255,7 @@
 }
 
 static void
-print_addresses(unsigned addrnr, struct in6_addr *addrp)
+print_addresses(unsigned int addrnr, struct in6_addr *addrp)
 {
 	unsigned int i;