If Skyrider can't fly due to being out of fuel, warn the player

git-svn-id: https://ja2svn.mooo.com/source/ja2/trunk/GameSource/ja2_v1.13/Build@8220 3b4a5df2-a311-0410-b5c6-a8a6f20db521

Strategic/mapscreen.cpp

@@ -15495,6 +15495,16 @@ void ExplainWhySkyriderCantFly( void )
 		return;
 	}
 
+	// travelled too far?
+	if ( gGameExternalOptions.fAlternativeHelicopterFuelSystem )
+	{
+		if ( iTotalHeliDistanceSinceRefuel > gHelicopterSettings.ubHelicopterDistanceWithoutRefuel )
+		{
+			DoMapMessageBox( MSG_BOX_BASIC_STYLE, pHelicopterRepairRefuelStrings[STR_HELI_TOOFAR_ERROR], MAP_SCREEN, MSG_BOX_FLAG_OK, MapScreenDefaultOkBoxCallback );
+			return;
+		}
+	}
+
 	// no explainable reason
 }