patch applied (packages/Cabal): Install haddock interface only when generated

[Ian Lynagh]

Mon Jun  9 12:02:51 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Install haddock interface only when generated
  This is actually Andrea Rossato's patch but it didn't merge
  cleanly due to more recent changes. Fixes ticket #250.

    M ./Distribution/Simple/Install.hs -4 +10

View patch online:
http://darcs.haskell.org/packages/Cabal/_darcs/patches/20080609190251-adfee-bc6a8e25c6fd682db37e533eca1f5d51d063422c.gz