forgot to add c in getopt

src/main.c

@@ -368,7 +368,7 @@ int main(int argc, char **argv) {
         struct ifreq ifr;
 
 
-        while ((option = getopt(argc, argv, "d:hf")) !=-1) {
+        while ((option = getopt(argc, argv, "d:hfc")) !=-1) {
                 switch (option) {
                         case 'd' :
                                 delay = atoi(optarg);