[cvs-nhc98] patch applied (cpphs): Recursively expand textual replacements in conditionals.

[Malcolm Wallace]

Tue Jun  5 02:16:40 PDT 2007  Malcolm.Wallace at cs.york.ac.uk
  * Recursively expand textual replacements in conditionals.
  (But parameterised macros are only expanded one level - not sure whether
   that is correct.)

    M ./Language/Preprocessor/Cpphs/CppIfdef.hs -2 +8