This prevents other processes from binding the same ports and
misusing the protocol/port-specific bypass rules installed in WFP to
bypass the VPN.
Fixes: 11e7d0677c ("socket-win: Install IKE bypass policies using bypass_socket()")
The use of overlapped I/O was incorrect, as we passed stack based buffers, but
did not cancel/wait for pending completion on all sockets. Our receive-from-all
socket interface is actually tricky to implement using overlapped I/O. Switch
to WSAEventSelect() event management, which can be canceled properly while
working in a select()-like way.