dwarf2out.c: do not short-circuit add_bound_info in array descr. lang-hook

dwarf2out.c: do not short-circuit add_bound_info in array descr. lang-hook

gcc/
	* dwarf2out.h (struct array_descr_info): Remove the base_decl field.
	* dwarf2out.c (enum dw_scalar_form): New.
	(struct loc_descr_context): New.
	(add_scalar_info): New.
	(add_bound_info): Add a context parameter.  Use add_scalar_info.
	(loc_list_from_tree): Add a context parameter.  Handle PLACEHOLDER_EXPR
	nodes for type-related expressions.  Likewise for base declarations.
	(loc_descriptor_from_tree): Add a context parameter.
	(subrange_type_die): Update calls to add_bound_info.
	(tls_mem_loc_descriptor): Likewise.
	(loc_list_for_address_of_addr_expr_of_indirect_ref): Add a context
	parameter.  Update calls to loc_list_from_tree.
	(add_subscript_info): Update calls to add_bound_info.
	(gen_array_type_die): Update calls to loc_list_from_tree and to
	add_bound_info.
	(descr_info_loc): Remove.
	(add_descr_info_field): Remove.
	(gen_descr_array_type_die): Switch add_descr_info_field calls into
	add_scalar_info/add_bound_info ones.
	(gen_subprogram_die): Update calls to loc_list_from_tree.
	(gen_variable_die): Likewise.

From-SVN: r218827