Gabor Greif authored Jan 05, 2012 and Simon Marlow committed Jan 06, 2012

The sizes obtained this way do not work on a target system in general.
So in a future cross-compilable setup we need another way of obtaining
expansions for the macros OFFSET, FIELD_SIZE and TYPE_SIZE.

Guarded against accidental use of 'sizeof' by poisoning.

Verified that the generated *Constants.h/hs files are unchanged.