Core/Entities: Use new PackedGuid class

src/server/scripts/Commands/cs_modify.cpp

@@ -964,14 +964,14 @@ public:
         target->Mount(mId);
 
         WorldPacket data(SMSG_FORCE_RUN_SPEED_CHANGE, (8+4+1+4));
-        data.append(target->GetPackGUID());
+        data << target->GetPackGUID();
         data << (uint32)0;
         data << (uint8)0;                                       //new 2.1.0
         data << float(speed);
         target->SendMessageToSet(&data, true);
 
         data.Initialize(SMSG_FORCE_SWIM_SPEED_CHANGE, (8+4+4));
-        data.append(target->GetPackGUID());
+        data << target->GetPackGUID();
         data << (uint32)0;
         data << float(speed);
         target->SendMessageToSet(&data, true);