Avoid checking ORPort reachability when the network is disabled

This is consistent with existing DirPort reachability checks.

changes/bug18616

@@ -1,7 +1,8 @@
   o Major bugfixes (directory mirrors):
     - Fix broken DirPort self-checks. Decide to advertise begindir
       support the same way we decide to advertise DirPorts.
-      Include additional config options in the list that might
-      change the content of a relay's descriptor.
+      Add additional config options that might change the content of
+      a relay's descriptor.
+      Avoid checking ORPort reachability when the network is disabled.
       Resolves #18616, bugfix on 0c8e042c30946faa in #12538 in
       0.2.8.1-alpha. Patch by "teor".

src/or/router.c

@@ -1085,6 +1085,7 @@ check_whether_orport_reachable(void)
 {
   const or_options_t *options = get_options();
   return options->AssumeReachable ||
+         net_is_disabled() ||
          can_reach_or_port;
 }