WriteInt in the ISO libraries should not emit '+' for positive values

WriteInt in the ISO libraries should not emit '+' for positive values

This trivial patch changes the default behaviour for WriteInt so that
'+' is not emitted when writing positive values.

gcc/m2/ChangeLog:

	* gm2-libs-iso/LongWholeIO.mod (WriteInt): Only request a
	sign if the value is < 0.
	* gm2-libs-iso/ShortWholeIO.mod (WriteInt): Only request a
	sign if the value is < 0.
	* gm2-libs-iso/WholeIO.mod (WriteInt): Only request a sign
	if the value is < 0.
	* gm2-libs-iso/WholeStr.mod (WriteInt): Only request a sign
	if the value is < 0.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>