[patch] beginnings of the macro rewrite

[Jeffrey A Law]

  In message < 20000421133913.D10427@wolery.cumb.org >you write:
  > 
  > *sigh* I was hoping 10 years past the adoption of C89 was long
  > enough.  This isn't Fortran, after all... :)
Don't be so sure.  I don't really expect traditional dialects of C to die
off any faster than F77 code has died off.

  > Are you familiar enough with any of those legacy code bases to know if
  > the following compromise position will be acceptable?
The whole point is we don't know about those code bases.

Please do not change the behavior of cpp when in traditional mode in regards
to recursive macros.

  > The C89 stringify and paste operators always work.
I do not think this is safe either.  We need to keep traditional working as
it has always worked.  This is a change that could potentially break user
code.

  > This mode should allow a relatively clean implementation of the
  > backward compatibility features - and at the same time it will permit
  > use of -traditional on systems with aggressively modern header files
  > (or anyway the preprocessor won't cause trouble).
I'm not worried much about -traditional causing problems on systems with
modern header files.  

jeff