Check if IP_TOS is defined before using.

regress/netcat.c

@@ -1181,11 +1181,13 @@ set_common_sockopts(int s)
 			&x, sizeof(x)) == -1)
 			err(1, "setsockopt");
 	}
+#ifdef IP_TOS
 	if (Tflag != -1) {
 		if (setsockopt(s, IPPROTO_IP, IP_TOS,
 		    &Tflag, sizeof(Tflag)) == -1)
 			err(1, "set IP ToS");
 	}
+#endif
 	if (Iflag) {
 		if (setsockopt(s, SOL_SOCKET, SO_RCVBUF,
 		    &Iflag, sizeof(Iflag)) == -1)
@@ -1201,6 +1203,7 @@ set_common_sockopts(int s)
 int
 map_tos(char *s, int *val)
 {
+#ifdef IP_TOS
 	/* DiffServ Codepoints and other TOS mappings */
 	const struct toskeywords {
 		const char	*keyword;
@@ -1242,6 +1245,7 @@ map_tos(char *s, int *val)
 			return (1);
 		}
 	}
+#endif
 
 	return (0);
 }