Drop -W from CFLAGS and some tiny code cleanups

- change "unsigned" to explicit "unsigned int"
- remove some casts
diff --git a/xtables.c b/xtables.c
index af4d3dc..dba9081 100644
--- a/xtables.c
+++ b/xtables.c
@@ -257,7 +257,7 @@
 
 u_int16_t parse_port(const char *port, const char *proto)
 {
-	unsigned portnum;
+	unsigned int portnum;
 
 	if ((string_to_number(port, 0, 65535, &portnum)) != -1 ||
 	    (portnum = service_to_port(port, proto)) != (unsigned)-1)