Fix p5_destroy_p5_object sometimes freeing bogus slots
Fix p5_destroy_p5_object sometimes freeing bogus slots

A ~ magic on an object alone doesn't mean it's magic created by Inline::Perl5.
Check the magic's key to make sure we actually get a valid index into the
object keeper's array and not some unrelated object or already freed slot.

niner/Inline-Perl5,niner/Inline-Perl5