fold-const.c (int_const_binop): Return NULL_TREE when an expression can't be evaluate...

fold-const.c (int_const_binop): Return NULL_TREE when an expression can't be evaluated at compile-time (instead...

	* fold-const.c (int_const_binop): Return NULL_TREE when an expression
	can't be evaluated at compile-time (instead of calling abort).
	Return NULL_TREE for division (and modulus) by zero.
	(const_binop):  Return NULL_TREE for floating point operators that
	aren't handled by real_arithmetic.
	(fold_binary):  Eliminate "wins" variable, and "binary" label, by
	folding operators with constant operands early.  Assert that
	operands are non-NULL.

From-SVN: r109088