Fix GCC error with URHO3D_SAFE_LUA=1. Closes #654.

Source/Urho3D/LuaScript/pkgs/LuaScript/LuaScriptInstance.pkg

@@ -139,6 +139,7 @@ static int tolua_LuaScriptLuaAPI_LuaScriptInstance_SubscribeToEvent(lua_State* t
 {
     int args = lua_gettop(tolua_S);
     tolua_Error tolua_err;
+    LuaScriptInstance* self = 0;
 
 #ifndef TOLUA_RELEASE
     if (args == 3)
@@ -162,7 +163,7 @@ static int tolua_LuaScriptLuaAPI_LuaScriptInstance_SubscribeToEvent(lua_State* t
         goto tolua_lerror;
 #endif
 
-    LuaScriptInstance* self = (LuaScriptInstance*)  tolua_tousertype(tolua_S,1,0);
+    self = (LuaScriptInstance*)  tolua_tousertype(tolua_S,1,0);
 
     if (args == 3)
     {
@@ -215,7 +216,8 @@ static int tolua_LuaScriptLuaAPI_LuaScriptInstance_UnsubscribeFromEvent(lua_Stat
 {
     int args = lua_gettop(tolua_S);
     tolua_Error tolua_err;
-    
+    LuaScriptInstance* self = 0;
+
 #ifndef TOLUA_RELEASE
     if (args == 2)
     {
@@ -236,7 +238,7 @@ static int tolua_LuaScriptLuaAPI_LuaScriptInstance_UnsubscribeFromEvent(lua_Stat
         goto tolua_lerror;
 #endif
 
-    LuaScriptInstance* self = (LuaScriptInstance*)  tolua_tousertype(tolua_S,1,0);
+    self = (LuaScriptInstance*)  tolua_tousertype(tolua_S,1,0);
 
     if (args == 2)
     {