* dwarf2read.c (dwarf2_attr_with_cu): New function, renamed

	* dwarf2read.c (dwarf2_attr_with_cu): New function, renamed
	from dwarf2_attr.  Also return the compilation unit associated
	with the attribute if we have followed a reference.  Complain
	if we return a reference attribute and the caller does not want
	the target compilation unit.
	(dwarf2_attr): Call dwarf2_attr_with_cu.
	(die_specification, dwarf2_extension): Also return a compilation
	unit.
	(follow_die_ref): Take attribute and compilation unit arguments.
	Call dwarf2_get_ref_die_offset.  Also return the target
	compilation unit.
	(read_func_scope, read_structure_scope): Update calls to
	die_specification.  Use the result.
	(read_namespace): Update call to dwarf2_extension.
	(namespace_name): Likewise.  Use the result.
	(new_symbol): Call dwarf2_attr_with_cu to check for DIE type.
	(die_type): Likewise.  Update call to follow_die_ref.  Use the
	results.
	(dwarf2_add_member_fn, read_structure_scope): Likewise for
	DW_AT_containing_type.
	(die_containing_type): Likewise.
	(die_is_declaration): Likewise for DW_AT_specification.