dwarf2: Change return type of predicate functions from int to bool

dwarf2: Change return type of predicate functions from int to bool

Also change some internal variables and function arguments from int to bool.

gcc/ChangeLog:

	* dwarf2asm.cc: Change FALSE to false.
	* dwarf2cfi.cc (execute_dwarf2_frame): Change return type to void.
	* dwarf2out.cc (matches_main_base): Change return type from
	int to bool.  Change "last_match" variable to bool.
	(dump_struct_debug): Change return type from int to bool.
	Change "matches" and "result" function arguments to bool.
	(is_pseudo_reg): Change return type from int to bool.
	(is_tagged_type): Ditto.
	(same_loc_p): Ditto.
	(same_dw_val_p): Change return type from int to bool and adjust
	function body accordingly.
	(same_attr_p): Ditto.
	(same_die_p): Ditto.
	(is_type_die): Ditto.
	(is_declaration_die): Ditto.
	(should_move_die_to_comdat): Ditto.
	(is_base_type): Ditto.
	(is_based_loc): Ditto.
	(local_scope_p): Ditto.
	(class_scope_p): Ditto.
	(class_or_namespace_scope_p): Ditto.
	(is_tagged_type): Ditto.
	(is_rust): Use void argument.
	(is_nested_in_subprogram): Change return type from int to bool.
	(contains_subprogram_definition): Ditto.
	(gen_struct_or_union_type_die): Change "nested", "complete"
	and "ns_decl" variables to bool.
	(is_naming_typedef_decl): Change FALSE to false.