Add game event flag for virtual train creation

src/openttd.cpp

@@ -1839,5 +1839,6 @@ char *DumpGameEventFlags(GameEventFlags events, char *b, const char *last)
 	dump('c', GEF_TRAIN_CRASH);
 	dump('i', GEF_INDUSTRY_CREATE);
 	dump('j', GEF_INDUSTRY_DELETE);
+	dump('v', GEF_VIRT_TRAIN);
 	return b;
 }

src/openttd.h

@@ -95,6 +95,7 @@ enum GameEventFlags : uint32 {
 	GEF_TRAIN_CRASH          = 1 << 5, ///< (c) A train crash has occurred
 	GEF_INDUSTRY_CREATE      = 1 << 6, ///< (i) An industry has been created (in game)
 	GEF_INDUSTRY_DELETE      = 1 << 7, ///< (j) An industry has been deleted (in game)
+	GEF_VIRT_TRAIN           = 1 << 8, ///< (v) A virtual train has been created
 };
 DECLARE_ENUM_AS_BIT_SET(GameEventFlags)
 

src/train_cmd.cpp

@@ -5255,6 +5255,8 @@ Train* CmdBuildVirtualRailVehicle(EngineID eid, StringID &error)
 		return nullptr;
 	}
 
+	RegisterGameEvents(GEF_VIRT_TRAIN);
+
 	if (rvi->railveh_type == RAILVEH_WAGON) {
 		return CmdBuildVirtualRailWagon(e);
 	}