function gammasgnf( x ) {
	return addon( x );
}
Computes the sign of the gamma function for a single-precision floating-point number.

@private
@param {number} x - input value
@returns {number} sign of the gamma function

@example
var v = gammasgnf( 1.0 );
// returns 1.0

v = gammasgnf( -2.5 );
// returns -1.0

v = gammasgnf( 0.0 );
// returns 0.0

v = gammasgnf( NaN );
// returns NaN