patch applied (cabal): Rework withTempFile code and use System.IO.openTempFile where available

[Duncan Coutts]

Wed Jan 23 15:58:47 PST 2008  Duncan Coutts <duncan at haskell.org>
  * Rework withTempFile code and use System.IO.openTempFile where available
  The System.IO.openTempFile is much better because it opens the temp files
  securely. Howver it is only available in base-2 and only of GHC. In base-3
  it is available for all implementations. So in practice that means it's only
  for GHC and we have to use our compatability implementation for hugs and
  nhc98. Not sure of the status for jhc.

    M ./Distribution/Compat/TempFile.hs -38 +18
    M ./Distribution/Simple/GHC.hs -5 +6
    M ./Distribution/Simple/Program.hs -4 +5
    M ./Distribution/Simple/Utils.hs -6 +11