patch applied (ghc-6.6/packages/unix): Provide nanosleep if we have it, and use it to implement usleep

[Simon Marlow]

Fri Mar  2 05:28:18 PST 2007  Simon Marlow <simonmar at microsoft.com>
  * Provide nanosleep if we have it, and use it to implement usleep
  Fixes #1156

    M ./System/Posix/Unistd.hsc -4 +40
    M ./configure.ac +1