libblkid: fix file descriptor leak in blkid_verify()

libblkid: fix file descriptor leak in blkid_verify()

The function blkid_verify() uses private device file descriptor and
uses blkid_probe_set_device() to assign the descriptor to low-level
probing code. Unfortunately, close() in this case is not enough as the
prober can internally open whole-disk device too.

The library API has been extended so blkid_probe_set_device()
deallocates and close previously used prober for whole-disk. This new
functionality is used in blkid_verify() now.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1734545
Signed-off-by: Karel Zak <kzak@redhat.com>