decl.c (annotate_value): Use test on the sign bit instead of on the sign of the value.

decl.c (annotate_value): Use test on the sign bit instead of on the sign of the value.

	* gcc-interface/decl.c (annotate_value) <INTEGER_CST>: Use test on
	the sign bit instead of on the sign of the value.
	<PLUS_EXPR>: Turn addition of negative constant into subtraction.
	<MULT_EXPR>: Add test for degenerate case.
	<BIT_AND_EXPR>: Simplify.

From-SVN: r268286