* fold-const.c (add_double): Rename to add_double_with_sign.
	Add 'unsigned_p' parameter and take it into account for the overflow.
	(mul_double): Rename to mul_double_with_sign. 
	Add 'unsigned_p' parameter and take it into account for the overflow.
	(fold_div_compare): Call add_double_with_sign instead of add_double
	and mul_double_with_sign instead of mul_double, passing them the
	unsignedness of the type.
	* tree.h (add_double): Macroize.
	(add_double_with_sign): New prototype.
	(mul_double): Macroize.
	(mul_double_with_sign): New prototype.

From-SVN: r117887