PREPROCESSOR library refactoring

From: Aleksey Gurtovoy (alexy_at_[hidden])
Date: 2002-03-10 00:24:06

As the result of upgrade to Metrowerks CW 7.2 I had to go through ~20 files
in 'boost/preprocessor' directory to update the numerous #ifdef's that all
looked like this:

    #if !defined(BOOST_NO_COMPILER_CONFIG) && defined(__MWERKS__) &&
(__MWERKS__ <= 0x2406)

Since it's unlikely that this is the last time we have to increment the
version here, and since I was going to modify these files anyway, I went
through all of them and replaced the above line by this one:

    #if !defined(BOOST_NO_COMPILER_CONFIG) &&
defined(BOOST_METROWERKS_PREPROCESSOR_BUGS)

I put the BOOST_METROWERKS_PREPROCESSOR_BUGS definition into
"boost/preprocessor/config.hpp" header (which I created for this sole
purpose), but, on second thought, moving it to
"boost/config/compiler/metrowerks.hpp" (and documenting as a part of
Boost.Config) might be a better idea (I can imagine that MPL might need it
as well). 

If everybody (and especially Vesa) is okay with the refactoring, I am going
to check it in. 

Aleksey