tree-chrec.c (chrec_convert_1): Only fold (T2)(t +- x) to (T2)t +- (T2)x if only integer types are involved.

	* tree-chrec.c (chrec_convert_1): Only fold (T2)(t +- x) to
	(T2)t +- (T2)x if only integer types are involved.

	* gcc.c-torture/compile/20091215-1.c: New test.

From-SVN: r155288