c++: CTAD and member function references [PR103943]

c++: CTAD and member function references [PR103943]

More quirks of rewriting member references to dependent references for
CTAD.  A reference to a member of dependent scope is definitely dependent.
And since r11-7044, tsubst_baselink builds a SCOPE_REF, so
tsubst_qualified_id should just use it.

	PR c++/103943

gcc/cp/ChangeLog:

	* pt.cc (tsubst_qualified_id): Handle getting SCOPE_REF from
	tsubst_baselink.
	(instantiation_dependent_scope_ref_p): Check dependent_scope_p.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/class-deduction109.C: New test.