sel-sched-ir.h: Make ilist_t work on insn_t rather than rtx

sel-sched-ir.h: Make ilist_t work on insn_t rather than rtx

gcc/
	* sel-sched-ir.h (ilist_t): Redefine this typedef in terms of
	ilist_t, not _xlist_t;
	(ILIST_INSN): Define in terms of new union field "insn".
	(ILIST_NEXT): Define in terms of _LIST_NEXT rather than
	_XLIST_NEXT.
	(struct _list_node): Add new field "insn" to the union, of type
	insn_t.
	(ilist_add): Replace macro with an inline function, requiring an
	insn_t.
	(ilist_remove): Define this macro directly in terms of
	_list_remove, rather than indirectly via _xlist_remove.
	(ilist_clear): Likewise, in terms of _list_clear rather than
	_xlist_clear.
	(ilist_is_in_p): Replace macro with an inline function, requiring
	an insn_t.
	(_list_iter_cond_insn): New function.
	(ilist_iter_remove): Define this macro directly in terms of
	_list_iter_remove, rather than indirectly via _xlist_iter_remove.
	(ilist_iterator): Define directly in terms of _list_iterator
	rather than indirectly through _xlist_iterator.
	(FOR_EACH_INSN): Define in terms of _list_iter_cond_insn rather
	than in terms of _FOR_EACH_X.
	(FOR_EACH_INSN_1): Likewise.

From-SVN: r214527