- avoids unnecessry interrupts

- Delays the release of the task (and its stacks) until the
  context switch has been completed

- network thread is able to wakeup directly the blocked threads
- reduce the number of context switches

- reduce the number of interrupts

see http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html
for more information

This reverts commit 6be9da0a37f1715778b6b7ea53c641963125555f.

if the time is already expired, the next timer will expire in 1ms

- acquire don't longer expect an absolute time as argument
- a maximum delay from calling the function is passed

- requires latest x86 crate

- barrier is necessary to avoid a race
- after the barrier all data structures are initialized