fold-const.c (fold_binary): Fold (X & 1) ^ 1 as (X & 1) == 0.

	* fold-const.c (fold_binary) <BIT_XOR_EXPR>: Fold (X & 1) ^ 1 as
	(X & 1) == 0.
	<BIT_AND_EXPR>: Fold (X ^ 1) & 1 and ~X & 1 as (X & 1) == 0.

	* gcc.dg/fold-even-1.c: New test case.

From-SVN: r111454