patch applied (cabal): call c2hs using the more detailed info

[Duncan Coutts]

Sun Apr 22 03:26:17 PDT 2007  Duncan Coutts <duncan.coutts at worc.ox.ac.uk>
  * call c2hs using the more detailed info
  we use --output-dir=dist/base
  and --output=<file relative to the search dir it was found in>.hs
  This actually depends on a patch in c2hs to make it treat --output-dir
  in the way we want. That patch will be forthcomming soonish.
  But the point is:
  c2hs --output-dir=dist/base --output=Foo/Bar.hs src/Foo/Bar.chs
  will generate dist/base/Foo/Bar.hs and also dist/base/Foo/Bar.h
  but inside the .hs file it'll reference Foo/Bar.h so when we compile the
  .hs file we have to -Idist/base
  Clear as mud?

    M ./Distribution/PreProcess.hs -5 +11