AP_HAL_SITL: set_cloexec on SITL's RCIN port

libraries/AP_HAL_SITL/SITL_State.cpp

@@ -118,11 +118,12 @@ void SITL_State::_setup_fdm(void)
 {
     if (!_sitl_rc_in.bind("0.0.0.0", _rcin_port)) {
         fprintf(stderr, "SITL: socket bind failed on RC in port : %d - %s\n", _rcin_port, strerror(errno));
-        fprintf(stderr, "Abording launch...\n");
+        fprintf(stderr, "Aborting launch...\n");
         exit(1);
     }
     _sitl_rc_in.reuseaddress();
     _sitl_rc_in.set_blocking(false);
+    _sitl_rc_in.set_cloexec();
 }
 #endif