fwprop.c: Use rtx_insn

fwprop.c: Use rtx_insn

gcc/
	* fwprop.c (single_def_use_dom_walker::before_dom_children):
	Strengthen local "insn" from rtx to rtx_insn *.
	(use_killed_between): Likewise for param "target_insn".
	(all_uses_available_at): Likewise for param "target_insn" and
	local "next".
	(update_df_init): Likewise for params "def_insn", "insn".
	(update_df): Likewise for param "insn".
	(try_fwprop_subst): Likewise for param "def_insn" and local
	"insn".
	(free_load_extend): Likewise for param "insn".
	(forward_propagate_subreg): Likewise for param "def_insn" and
	local "use_insn".
	(forward_propagate_asm): Likewise for param "def_insn" and local
	"use_insn".
	(forward_propagate_and_simplify): Likewise for param "def_insn"
	and local "use_insn".
	(forward_propagate_into): Likewise for locals "def_insn" and
	"use_insn".

From-SVN: r214328