C++ PATCH to unify

[Jason Merrill]

This patch fixes two regressions from 2.95 involving a deduced type with
greater cv-qualification than the argument type.  

First, we were failing for pointers to members because the OFFSET_TYPE
wasn't considered const; I've fixed this by avoiding the recursion there.
In the future, we should do away with the POINTER_TYPE to OFFSET_TYPE
nonsense.

Second, we were checking the cv-quals on the argument type, when it should
have been the parameter type.

Tests below.  Tested i686-pc-linux-gnu, applied to trunk.  This should
certainly go into 3.0.1, but probably not 3.0 at this point.  Mark, do you
agree?

2001-06-14  Jason Merrill  <jason_merrill@redhat.com>

	* pt.c (unify): Don't recurse between the POINTER_TYPE and the
	OFFSET_TYPE.  If we're adding cv-quals, the extra ones would be on
	PARM, not ARG.