A mistake from 90ea8e89d9b7 is that in6_pcblookup_internal() was skipped
for an inpcb that had unspecified local address. This is incorrect, as
such inpcb could have already have a port set, and in_pcb_lport_dest()
shall not be called on such inpcb. That could lead to creation of an
alised connection in the database.
This makes the function almost identical to in_pcbconnect(). While here,
fix minor bug of missing INP_ANONPORT. This flag has no use in kernel,
but affects netstat(1) output in certain mode.