fold-const.c (fold): Optimize unsigned modulus by a power of two into a bit-wise...

fold-const.c (fold): Optimize unsigned modulus by a power of two into a bit-wise AND, i.e.

	* fold-const.c (fold) <TRUNC_MOD_EXPR>: Optimize unsigned modulus
	by a power of two into a bit-wise AND, i.e. "X % C" as "X & (C-1)".
	Normalize "X % C" as "X % -C" for signed modulus and negative C.
	Optimize "X % -Y" as "X % Y" for signed modulus.
	<EQ_EXPR>: Recursively call "fold" when transforming "(X % Y) == 0"
	into "((unsigned) X % Y) == 0".

From-SVN: r84122