optimise @array in boolean context

optimise @array in boolean context

It's quicker to return (and to test for) &PL_sv_zero or &PL_sv_yes,
than setting a targ to an integer value or, in the vase of padav,
creating a mortal sv and setting it to an integer value.

In fact for padav, even in the scalar but non-boolean case, return
&PL_sv_zero if the value is zero rather than creating and setting a mortal.