the initialization of m_pkts with an int threw an error with
17.7P3 since it decided int -> uint64_t required a narrowing
conversion. Not sure why it got picky here all of a sudden
but given it's not wrong, we may as well fix it properly.
This change changes the queueSize parameter to size_t and
adds a bounds check at the calling site to ensure the value
it gets will be positive before casting.
1058fd1b2b