Fix threadDelay on Windows; fixes ThreadDelay001 failures

MSDN says of Sleep:
    If dwMilliseconds is greater than one tick but less than two, the
    wait can be anywhere between one and two ticks, and so on.
so we need to add (milliseconds-per-tick - 1) to the amount of time we
sleep for.
Merge branch 'master' of darcs.haskell.org:/srv/darcs//ghc
Merge branch 'master' of darcs.haskell.org:/srv/darcs//ghc