vbox: Fix resource leak
vbox: Fix resource leak

Need to free the allocated hardDiskToOpen array. The contents of the
array are just pointers returned by virVBoxSnapshotConfHardDiskByLocation
and not allocated AFAICT so they don't need to also be freed as well.

Found by Coverity

Signed-off-by: John Ferlan <87558058f6f829e5ec976c8ef960720af4ff9c7d@redhat.com>
Reviewed-by: Katerina Koukiou <e327f8a3293ed5cbf737faab85e97cd2d0b8b9c3@redhat.com>

eskultety/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,eskultety/libvirt,libvirt/libvirt,zippy2/libvirt,fabianfreyer/libvirt,zippy2/libvirt,crobinso/libvirt,libvirt/libvirt,eskultety/libvirt,jardasgit/libvirt,jardasgit/libvirt,crobinso/libvirt,eskultety/libvirt,andreabolognani/libvirt,jardasgit/libvirt,andreabolognani/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,zippy2/libvirt,olafhering/libvirt,libvirt/libvirt,crobinso/libvirt,zippy2/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,olafhering/libvirt,jfehlig/libvirt,olafhering/libvirt,andreabolognani/libvirt,olafhering/libvirt,nertpinx/libvirt,nertpinx/libvirt,nertpinx/libvirt,eskultety/libvirt,andreabolognani/libvirt