PR c++/92206 - ICE with typedef to dependent alias.

PR c++/92206 - ICE with typedef to dependent alias.

rsandifo's patch for 92206 demonstrated a problem with the existing checking
for alias template specializations: they were returning false for a typedef
to an alias template specialization.  Which is sometimes what the caller
wants, and sometimes not: Sometimes we're interested in whether the type was
written as an alias template-id, and sometimes whether it represents one.

The testcase illustrates a case that remained wrong with the earlier patch:
if the typedef is itself an alias template specialization, we can't strip an
underlying dependent alias.

	* pt.c (dependent_alias_template_spec_p)
	(alias_template_specialization_p): Add transparent_typedefs
	parameter.
	(iterative_hash_template_arg, any_template_parm_r)
	(primary_template_specialization_p, tsubst, dependent_type_p_r):
	Adjust.
	* decl.c (check_elaborated_type_specifier): Adjust.
	* error.c (dump_template_bindings, dump_aggr_type): Adjust.

From-SVN: r278784