Add -p PORT command-line parameter.

FIXME: at this point, the port parameter set in the configuration
file will take precedence over the command-line argument. It should
be the opposite.

src/main.c

@@ -173,7 +173,7 @@ process_cmdline (int argc, char **argv, struct config_s *conf)
 {
         int opt;
 
-        while ((opt = getopt (argc, argv, "c:vdh")) != EOF) {
+        while ((opt = getopt (argc, argv, "c:p:vdh")) != EOF) {
                 switch (opt) {
                 case 'v':
                         display_version ();
@@ -196,6 +196,10 @@ process_cmdline (int argc, char **argv, struct config_s *conf)
                         }
                         break;
 
+                case 'p':
+                        conf->port = strtol(optarg, NULL, 10);
+                        break;
+
                 case 'h':
                         display_usage ();
                         exit (EX_OK);