Remove bogus io_noblocking() from player_login()

The call switched the connection with the player to blocking I/O for
draining of output before closing the connection.  Looks scary,
because blocking on I/O blocks the complete server process, not just
the player thread.  But we don't do input, and we do output only with
IO_WAIT, which can't block.  So this has no effect.

src/lib/player/login.c

@@ -118,7 +118,6 @@ player_login(void *ud)
     player->state = PS_SHUTDOWN;
     if (!io_eof(player->iop)) {
 	pr_id(player, C_EXIT, "so long...\n");
-	io_noblocking(player->iop, 0);
 	while (io_output(player->iop, IO_WAIT) > 0) ;
     }
     player_delete(player);