* dwarf2out.c (dwarf_attr_name): Map DW_AT_GNAT_descriptive_type.
	(add_gnat_descriptive_type_attribute): New function.
	(gen_array_type_die): Call it.
	(gen_enumeration_type_die): Likewise.
	(gen_struct_or_union_type_die): Likewise.
	(modified_type_die): Likewise.
	* langhooks.h (lang_hooks_for_types): New descriptive_type hook.
	* langhooks-def.h (LANG_HOOKS_DESCRIPTIVE_TYPE): Default to NULL.
	(LANG_HOOKS_FOR_TYPES_INITIALIZER): Add LANG_HOOKS_DESCRIPTIVE_TYPE.
ada/
	* gcc-interface/misc.c (gnat_descriptive_type): New function.
	(LANG_HOOKS_DESCRIPTIVE_TYPE): Redefine to gnat_descriptive_type.

Co-Authored-By: Eric Botcazou <ebotcazou@adacore.com>
Co-Authored-By: Nicolas Setton <setton@adacore.com>

From-SVN: r171862