m2: use _P() defines from tree.h

m2: use _P() defines from tree.h

gcc/m2/ChangeLog:

	* gm2-gcc/m2builtins.cc (doradix): Use _P defines from tree.h.
	(doplaces): Ditto.
	(doexponentmin): Ditto.
	(doexponentmax): Ditto.
	(dolarge): Ditto.
	(dosmall): Ditto.
	(dogUnderflow): Ditto.
	* gm2-gcc/m2convert.cc (unsafe_conversion_p): Ditto.
	* gm2-gcc/m2expr.cc (m2expr_build_unary_op_check): Ditto.
	(m2expr_build_binary_op_check): Ditto.
	* gm2-gcc/m2tree.cc (m2tree_is_var): Ditto.
	* gm2-gcc/m2treelib.cc (build_modify_expr): Ditto.
	* gm2-gcc/m2type.cc (gm2_finish_decl): Ditto.
	* m2pp.cc (hextree): Ditto.
	(m2pp_call_expr): Ditto.