Copter: Add GCS failsafe pre-arm check

ArduCopter/AP_Arming.cpp

@@ -60,7 +60,8 @@ bool AP_Arming_Copter::run_pre_arm_checks(bool display_failure)
         & parameter_checks(display_failure)
         & motor_checks(display_failure)
         & pilot_throttle_checks(display_failure)
-        & oa_checks(display_failure) &
+        & oa_checks(display_failure)
+        & gcs_failsafe_check(display_failure) &
         AP_Arming::pre_arm_checks(display_failure);
 }
 
@@ -563,6 +564,15 @@ bool AP_Arming_Copter::mandatory_gps_checks(bool display_failure)
     return true;
 }
 
+// Check GCS failsafe
+bool AP_Arming_Copter::gcs_failsafe_check(bool display_failure)
+{
+    if (copter.failsafe.gcs) {
+        check_failed(display_failure, "GCS failsafe on");
+        return false;
+    }
+    return true;
+}
 
 // arm_checks - perform final checks before arming
 //  always called just before arming.  Return true if ok to arm

ArduCopter/AP_Arming.h

@@ -49,6 +49,7 @@ protected:
     bool pilot_throttle_checks(bool display_failure);
     bool oa_checks(bool display_failure);
     bool mandatory_gps_checks(bool display_failure);
+    bool gcs_failsafe_check(bool display_failure);
 
     void set_pre_arm_check(bool b);