Use rtx_insn_list within haifa-sched.c

Use rtx_insn_list within haifa-sched.c

gcc/ChangeLog:
2014-09-05  David Malcolm  <dmalcolm@redhat.com>

	* haifa-sched.c (check_clobbered_conditions): Strengthen local
	"link" from rtx to rtx_insn_list *, and use its methods for
	clarity and type-safety.
	(toggle_cancelled_flags): Likewise.
	(restore_last_backtrack_point): Likewise.
	(queue_to_ready): Use insn method of "link" in one place.
	(schedule_block): Strengthen local "link" from rtx to
	rtx_insn_list *, and use its methods for clarity and type-safety.

From-SVN: r214968