patch applied (ghc): remove #if branches for pre-ghc-6.0

[Isaac Dupree]

Tue Jun  5 16:53:01 PDT 2007  Isaac Dupree <id at isaac.cedarswampstudios.org>
  * remove #if branches for pre-ghc-6.0
  I skipped utils/hsc2hs/Main.hs since its ifs also involved
  checking for old versions of nhc98 (I don't want to figure that out),
  but removed everything else I found relating to building with pre-6.0

    M ./compiler/ghci/InteractiveUI.hs -4 +1
    M ./compiler/main/GHC.hs -6 +1
    M ./compiler/main/SysTools.lhs -8 +1
    M ./compiler/utils/Binary.hs -10
    M ./compiler/utils/FastString.lhs -15 +1
    M ./compiler/utils/Panic.lhs -8
    M ./compiler/utils/StringBuffer.lhs -15
    M ./utils/genapply/GenApply.hs -9
    M ./utils/ghc-pkg/Main.hs -17