Copter: enable tail pass thru in acro for EXTGYRO tails

this allows acro mode to function as full passthru

ArduCopter/flight_mode.cpp

@@ -240,7 +240,7 @@ void Copter::exit_mode(uint8_t old_control_mode, uint8_t new_control_mode)
 #if FRAME_CONFIG == HELI_FRAME
     // firmly reset the flybar passthrough to false when exiting acro mode.
     if (old_control_mode == ACRO) {
-        attitude_control.use_flybar_passthrough(false);
+        attitude_control.use_flybar_passthrough(false, false);
     }
 
     // reset RC Passthrough to motors

ArduCopter/heli_control_acro.cpp

@@ -11,7 +11,7 @@
 bool Copter::heli_acro_init(bool ignore_checks)
 {
     // if heli is equipped with a flybar, then tell the attitude controller to pass through controls directly to servos
-    attitude_control.use_flybar_passthrough(motors.has_flybar());
+    attitude_control.use_flybar_passthrough(motors.has_flybar(), motors.tail_type() == AP_MOTORS_HELI_TAILTYPE_SERVO_EXTGYRO);
 
     // always successfully enter acro
     return true;