rollback the attempt to fix version trouble

Instead, it forced all packages to be recompiled all the time.
Things are not as easy as they seem...

rolling back:

Thu May 27 23:28:21 CEST 2010  Lennart Kolmodin <kolmodin@gentoo.org>
  * bugfix: ghc version x.y.z is not same as version x.y
  haskell-updater was treating ghc 6.12.2.20100521 as the same version as
  6.12.2, this patch makes it into two separate versions.

    M ./Distribution/Gentoo/GHC.hs -1 +1

Distribution/Gentoo/GHC.hs

@@ -129,7 +129,7 @@ checkLibDir thisGhc libDir = pkgsHaveContent (hasDirMatching wanted)
     isValid = isGhcLibDir libDir
 
     -- Invalid if it's this GHC
-    isInvalid = BS.isPrefixOf (BS.append thisGhc (BS.pack "/"))
+    isInvalid = BS.isPrefixOf thisGhc
 
 -- A valid GHC library directory starting at libdir has a name of
 -- either "ghc" or "ghc-bin", then a hyphen and then a version number.