PR bootstrap/44255
	* combine.c (struct rtx_subst_pair): Define unconditionally.
	(propagate_for_debug_subst): Likewise.  If not AUTO_INC_DEC,
	copy_rtx pair->to instead of cleanup_auto_inc_dec it.
	Call make_compound_operation on pair->to.
	(propagate_for_debug): Don't call make_compound_operation here.
	Always use simplify_replace_fn_rtx.

From-SVN: r159952