qt: Fix missing qRegisterMetaType for size_t
qt: Fix missing qRegisterMetaType for size_t

It is required in order to use size_t in QueuedConnections.


Former-commit-id: 1041bee56c40b3622c8d0d80f2860d98aeb1332d
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin