function nullary0d( x, fcn ) {
	x.data[ x.offset ] = fcn();
}
Applies a nullary function and assigns results to elements in an output ndarray.

@private
@param {Object} x - object containing ndarray meta data
@param {string} x.dtype - data type
@param {Collection} x.data - data buffer
@param {NonNegativeIntegerArray} x.shape - dimensions
@param {IntegerArray} x.strides - stride lengths
@param {NonNegativeInteger} x.offset - index offset
@param {string} x.order - specifies whether `x` is row-major (C-style) or column-major (Fortran-style)
@param {Callback} fcn - nullary callback
@returns {void}

@example
var Float64Array = require( '@stdlib/array/float64' );

function fcn() {
    return 10.0;
}

// Create a data buffer:
var xbuf = new Float64Array( 2 );

// Define the shape of the output array:
var shape = [];

// Define the array strides:
var sx = [ 0 ];

// Define the index offset:
var ox = 1;

// Create the output ndarray-like object:
var x = {
    'dtype': 'float64',
    'data': xbuf,
    'shape': shape,
    'strides': sx,
    'offset': ox,
    'order': 'row-major'
};

// Apply the nullary function:
nullary0d( x, fcn );

console.log( x.data );
// => <Float64Array>[ 0.0, 10.0 ]