[PATCH] Futex update.

[PATCH] Futex update.

This changes futex semantics to a simple "sleep if this address
equals this value" interface, which is more convenient for building
other primitives.  It also adds a timeout value.

Example library can be found at:
   http://www.kernel.org/pub/linux/kernel/people/rusty/futex-2.0.tar.gz