* name-lookup.c (struct scope_binding): New.
	(EMPTY_SCOPE_BINDING): New.
	(lookup_using_namespace): Take a scope_binding instead of a
	cxx_binding.
	(qualified_lookup_using_namespace): Likewise.
	(cxx_binding_clear): Delete.
	(do_nonmember_using_decl): Use a scope_binding instead of a
	cxx_binding.
	(lookup_tag): Don't call select_decl.
	(ambiguous_decl): Don't return anything (and change callers to match).
	Take a scope_binding as the second parameter.
	(lookup_namespace_name): Use a scope_binding instead of a
	cxx_binding.
	(unqualified_namespace_lookup): Likewise.
	(lookup_qualified_name): Likewise.
	(select_decl): Take a scope_binding instead of a cxx_binding.
	Use macros rather than hand-coding tests for type-ness.

From-SVN: r81864