c++: alias_ctad_tweaks ICE w/ inherited CTAD [PR119687]

c++: alias_ctad_tweaks ICE w/ inherited CTAD [PR119687]

With inherited CTAD the set of guides may be a two-dimensional overload
set (i.e. OVERLOADs of OVERLOADs) so alias_ctad_tweaks (which also does
the inherited CTAD transformation) needs to use the 2D-aware lkp_iterator
instead of ovl_iterator, or better yet use the more idiomatic lkp_range.

	PR c++/119687

gcc/cp/ChangeLog:

	* pt.cc (alias_ctad_tweaks): Use lkp_range / lkp_iterator
	instead of ovl_iterator.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp23/class-deduction-inherited8.C: New test.

Reviewed-by: Jason Merill <jason@redhat.com>