h8300-protos.h: Update the prototype for split_adds_subs.

h8300-protos.h: Update the prototype for split_adds_subs.

	* config/h8300/h8300-protos.h: Update the prototype for
	split_adds_subs.
	Add prototypes for const_le_2_operand and const_le_6_operand.
	* config/h8300/h8300.c (split_adds_subs): Add an argument to
	specify whether inc/dec should be used when possible.
	(const_le_2_operand): New.
	(const_le_6_operand): Likewise.
	* config/h8300/h8300.md (two peepholes): New.

From-SVN: r60387