Helicity Amplitudes for Order <i>alpha<sub>s</sub></i> Production of <i>W<sup>+</sup>W<sup>-</sup></i>, <i>W<sup>+-</sup>Z</i>, <i>ZZ</i>, <i>W<sup>+-</sup>gamma</i>, or <i>Z gamma</i> Pairs at Hadron Colliders