Merge branch 'master' of github.com:cloudius-systems/osv

* 'master' of github.com:cloudius-systems/osv:
  main: minimal nanosleep() test
  libc: implement nanosleep()
  sched: add sleep_until()
  sched: fix segfault switching a thread back to itself
  kvmclock: fix for physical mapping changes
  build: disable the x86-64 redzone for now
  implement dup3()