get_ebb_head_tail works with rtx_insn

get_ebb_head_tail works with rtx_insn

gcc/
	* sched-int.h (get_ebb_head_tail): Strengthen params "headp" and
	"tailp" from rtx * to rtx_insn **.

	* ddg.c (build_intra_loop_deps): Strengthen locals head", "tail"
	from rtx to rtx_insn *.
	* haifa-sched.c (get_ebb_head_tail): Strengthen params "headp" and
	"tailp" from rtx * to rtx_insn **.  Strengthen locals "beg_head",
	"beg_tail", "end_head", "end_tail", "note", "next", "prev" from
	rtx to rtx_insn *.
	* modulo-sched.c (const_iteration_count): Strengthen return type
	and locals "insn", "head", "tail" from rtx to rtx_insn *.  Replace
	use of NULL_RTX with NULL when working with insns.
	(loop_single_full_bb_p): Strengthen locals "head", "tail" from rtx
	to rtx_insn *.
	(sms_schedule): Likewise.
	* sched-rgn.c (init_ready_list): Likewise, also for locals
	"src_head" and "src_next_tail".
	(compute_block_dependences): Likewise.
	(free_block_dependencies): Likewise.
	(debug_rgn_dependencies): Likewise.
	(free_rgn_deps): Likewise.
	(compute_priorities): Likewise.
	(schedule_region): Likewise.
	* sel-sched.c (find_ebb_boundaries): Likewise.

	* config/sh/sh.c (find_insn_regmode_weight): Strengthen locals
	"insn", "next_tail", "head", "tail" from rtx to rtx_insn *.

From-SVN: r214352