DWARF: add a language hook for fixed-point types

DWARF: add a language hook for fixed-point types

Support for fixed-point types in GCC is not powerful enough for Ada
fixed-point types: GNAT uses regular scalar types to implement them.
This new language hook makes it possible to output the desired debugging
information anyway.

gcc/ada/ChangeLog:

	* gcc-interface/ada-tree.def (POWER_EXPR): New binary operation.
	* gcc-interface/ada-tree.h (TYPE_FIXED_POINT_P): New macro.
	(TYPE_IS_FIXED_POINT_P): New macro.
	(TYPE_SCALE_FACTOR): New macro.
	(SET_TYPE_SCALE_FACTOR): New macro.
	* gcc-interface/decl.c: Include urealp.h
	(gnat_to_gnu_entity): Attach trees to encode scale factors to
	fixed-point types.
	* gcc-interface/misc.c (gnat_print_type): Print scale factors
	for fixed-point types.
	(gnat_get_fixed_point_type_info): New.
	(gnat_init_ts): Initialize data for the POWER_EXPR binary
	operation.
	(LANG_HOOKS_GET_FIXED_POINT_INFO): Redefine macro to implement
	the get_fixed_point_type_info language hook.

gcc/ChangeLog:

	* langhooks.h (struct lang_hooks_for_types): Add a
	get_fixed_point_type_info field.
	* langhooks-def.h (LANG_HOOKS_GET_FIXED_POINT_TYPE_INFO): New
	macro.
	(LANG_HOOKS_FOR_TYPES_INITIALIZER): Initialize the
	get_fixed_point_type_info field.
	* dwarf2out.h (enum fixed_point_scale_factor): New.
	(struct fixed_point_type_info): New.
	* dwarf2out.c (base_type_die): In DWARFv3 or non-strict DWARF
	mode, get fixed-point type information using the debugging hook
	and describe it in DWARF, if any.

From-SVN: r231764