Copter: bug fix for throttle failsafe

Missing bracket could cause throttle failsafe to be triggered even when
disabled or motors disarmed

ArduCopter/radio.pde

@@ -124,8 +124,8 @@ static void read_radio()
     }else{
         uint32_t elapsed = millis() - last_update;
         // turn on throttle failsafe if no update from the RC Radio for 500ms or 2000ms if we are using RC_OVERRIDE
-        if ((!failsafe.rc_override_active && (elapsed >= FS_RADIO_TIMEOUT_MS)) || (failsafe.rc_override_active && (elapsed >= FS_RADIO_RC_OVERRIDE_TIMEOUT_MS))
-            && g.failsafe_throttle && motors.armed() && !failsafe.radio) {
+        if (((!failsafe.rc_override_active && (elapsed >= FS_RADIO_TIMEOUT_MS)) || (failsafe.rc_override_active && (elapsed >= FS_RADIO_RC_OVERRIDE_TIMEOUT_MS))) &&
+            (g.failsafe_throttle && motors.armed() && !failsafe.radio)) {
             Log_Write_Error(ERROR_SUBSYSTEM_RADIO, ERROR_CODE_RADIO_LATE_FRAME);
             set_failsafe_radio(true);
         }