reg-stack: Change return type of predicate functions from int to bool

reg-stack: Change return type of predicate functions from int to bool

Also change some internal variables to bool and recode handling of
boolean varialbes to not use bitwise or.

gcc/ChangeLog:

	* rtl.h (stack_regs_mentioned): Change return type from int to bool.
	* reg-stack.cc (struct_block_info_def): Change "done" to bool.
	(stack_regs_mentioned_p): Change return type from int to bool
	and adjust function body accordingly.
	(stack_regs_mentioned): Ditto.
	(check_asm_stack_operands): Ditto.  Change "malformed_asm"
	variable to bool.
	(move_for_stack_reg): Recode handling of control_flow_insn_deleted.
	(swap_rtx_condition_1): Change return type from int to bool
	and adjust function body accordingly.  Change "r" variable to bool.
	(swap_rtx_condition): Change return type from int to bool
	and adjust function body accordingly.
	(subst_stack_regs_pat): Recode handling of control_flow_insn_deleted.
	(subst_stack_regs): Ditto.
	(convert_regs_entry): Change return type from int to bool and adjust
	function body accordingly.  Change "inserted" variable to bool.
	(convert_regs_1): Recode handling of control_flow_insn_deleted.
	(convert_regs_2): Recode handling of cfg_altered.
	(convert_regs): Ditto.  Change "inserted" variable to bool.