cleanup libc FILE locking?

[David Xu <davidxu@xxxxxxxx>]

Is there anyone doing the dirty work ?
Last time, we tested Dave's crew example, and it crashed on someone's
machine, I think that is related to libc FILE locking, I don't have
FILE locking in the libthread_xu, and don't want to do such nasty
thing in thread library, that should be done in libc itself and e.g
use pthread mutex.

David Xu