Introduce new typedefs: const_tree, const_rtx, etc.

[Kaveh R. Ghazi]

 > This kind of change is so massive across the source base that it will
 > disrupt almost all work currently being done on branches.  Therefore,
 > I will pre-approve this change and the follow-on patches to use the
 > types for stage *2*.  However, even at this point, please make sure
 > that we have flushed the outstanding branch patches for the next
 > release before applying.  I agree that this change is an improvement,
 > but it would be bad for a change of this nature to interfere with the
 > contribution of important new technology.

That sounds prudent, okay and thanks.

However how will I know we've "flushed" all the projects?  I.e. have
we created a 4.3 projects page so I will know which branches are
supposed to be merged and have a way to measure completion?  (I didn't
see a new projects page on the wiki.)

Or perhaps you could just tell me what the branches are if the list is
already known and small.

In the mean time I'll continue to post patches so they get a little
scrutiny.

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