* loop.h (total_biv_increment): Constify iv_class pointer.
	(struct induction): Replace `mem_mode' with `mem' rtx.
	* unroll.c (total_biv_increment): Constify iv_class pointer.
	* loop.c (loop_giv_reduce_benefit): Derive mem mode from mem rtx.
	(find_mem_givs, combine_givs_p): Likewise.
	(debug_ivs, debug_iv_class, loop_ivs_dump, loop_iv_class_dump): New.

From-SVN: r38933