regrename.c: Use rtx_insn

regrename.c: Use rtx_insn

gcc/
	* regrename.c (create_new_chain): Strengthen param "insn" from rtx
	to rtx_insn *.
	(init_rename_info): Replace use of NULL_RTX with NULL when dealing
	with an insn.
	(regrename_analyze): Strengthen local "insn" from rtx to
	rtx_insn *.
	(scan_rtx_reg): Likewise for param "insn".
	(scan_rtx_address): Likewise.
	(scan_rtx): Likewise.
	(restore_operands): Likewise.
	(record_out_operands): Likewise.
	(build_def_use): Likewise for local "insn".  Replace use of
	NULL_RTX with NULL when dealing with an insn.

From-SVN: r214368