PATCH[b-i=b]: Change cpp_hashnode.directive_index to a bit-field

[Kaveh R. Ghazi]

 > I wonder:  Are there actually still any machines that have signed
 > bitfields, supported as gcc hosts?

Yes.  Solaris2 cc has unsigned bitfields whereas irix6 cc has signed
bitfields by default.  I got bitten by this in the new real.[ch]
implementation which relies on signed bitfields.  See:
http://gcc.gnu.org/ml/gcc-patches/2002-09/msg01433.html

I fixed it for solaris2 by using the `signed' keyword to the relevant
field, (ansidecl.h handles defining `signed' to nothing for K&R C.)

Since we appear to have a solution for ISO C, IMHO the real question
is whether there are any >>K&R C<< compilers out there which we
support and which are unsigned by default.  I think only hpux cc
possibly qualifies, and no one has reported a problem in the three
months since the new real.c implementation was installed.  Perhaps
someone with access to these platforms could confirm?

If this holds, I believe we could use `signed' and be done with it.

		--Kaveh
--
Kaveh R. Ghazi			ghazi@caip.rutgers.edu