patch applied (cabal): Add configure --docdir flag which defaults to "$datadir/doc/$pkgid"

[Duncan Coutts]

Wed Aug 15 18:16:34 PDT 2007  Duncan Coutts <duncan at haskell.org>
  * Add configure --docdir flag which defaults to "$datadir/doc/$pkgid"
  Fixes bug #140

    M ./Distribution/Setup.hs +8
    M ./Distribution/Simple/Configure.hs -4 +4
    M ./Distribution/Simple/InstallDirs.hs -1 +1