untie PD handle on DESTORYing

... so that File::Temp can remove the temporary 02packages safely under Win32

cf. http://www.cpantesters.org/distro/C/CPAN-Common-Index.html#CPAN-Common-Index-0.003?grade=1&perlmat=2&patches=2&oncpan=2&distmat=2&perlver=ALL&osname=mswin32&version=0.003