loop-unroll.c: Use rtx_insn (also touches basic-block.h)

loop-unroll.c: Use rtx_insn (also touches basic-block.h)

gcc/
	* basic-block.h (basic_block split_edge_and_insert): Strengthen
	param "insns" from rtx to rtx_insn *.

	* loop-unroll.c (struct iv_to_split): Strengthen field "insn" from
	rtx to rtx_insn *.
	(struct iv_to_split): Likewise.
	(loop_exit_at_end_p): Likewise for local "insn".
	(split_edge_and_insert): Likewise for param "insns".
	(compare_and_jump_seq): Likewise for return type, param "cinsn",
	and locals "seq", "jump".
	(unroll_loop_runtime_iterations): Likewise for locals "init_code",
	"branch_code"; update invocations of compare_and_jump_seq to
	eliminate NULL_RTX in favor of NULL.
	(referenced_in_one_insn_in_loop_p): Strengthen local "insn" from
	rtx to rtx_insn *.
	(reset_debug_uses_in_loop): Likewise.
	(analyze_insn_to_expand_var): Likewise for param "insn".
	(analyze_iv_to_split_insn): Likewise.
	(analyze_insns_in_loop): Likewise for local "insn".
	(insert_base_initialization): Likewise for param
	"insn" and local "seq".
	(split_iv): Likewise for param "insn" and local "seq".
	(expand_var_during_unrolling): Likewise for param "insn".
	(insert_var_expansion_initialization): Likewise for local "seq".
	(combine_var_copies_in_loop_exit): Likewise.
	(combine_var_copies_in_loop_exit): Likewise for locals "seq" and
	"insn".
	(maybe_strip_eq_note_for_split_iv): Likewise for param "insn".
	(apply_opt_in_copies): Likewise for locals "insn", "orig_insn",
	"next".

From-SVN: r214345