* autoload.cc: Add autoload statements for ws2_32 functions

`WSACloseEvent', `WSACreateEvent', `WSAGetOverlappedResult',
        `WSARecv', `WSARecvFrom', `WSASend', `WSASendTo' and `WSASetEvent',
        `WSAWaitForMultipleEvents'.
        * net.cc: Define wsock_evt.
        (wsock_event): New class.
        (cygwin_sendto): Use overlapped socket io if available.
        (cygwin_recvfrom): Ditto.
        (cygwin_recv): Ditto.
        (cygwin_send): Ditto.
        * security.cc (subauth): Set Win32 error to 0 to safely ask for the
        error code of dynamically loaded function `LsaRegisterLogonProcess'.

winsup/cygwin/security.cc

@@ -188,6 +188,7 @@ subauth (struct passwd *pw)
 
   /* Register as logon process. */
   str2lsa (name, "Cygwin");
+  SetLastError (0);
   ret = LsaRegisterLogonProcess(&name, &lsa_hdl, &sec_mode);
   if (ret != STATUS_SUCCESS)
     {