(pfn_WSACreateEvent, pfn_WSACloseEvent): New func ptrs.

(pfn_WSACreateEvent, pfn_WSACloseEvent): New func ptrs.
(init_winsock): Load them.  Use ws2_32.dll.
(sys_listen): Undo last change.  Just set FILE_LISTEN flag.
(sys_accept): Undo last change.  Instead, set child status to
STATUS_READ_ACKNOWLEDGED and reset char_avail event so next
sys_select will wakeup the reader thread.
(_sys_wait_accept): New function used by reader thread to wait for
an incoming connection on a server socket.