mount: generic blkid/volume_id wrapper, use blkid_evaluate_*

mount: generic blkid/volume_id wrapper, use blkid_evaluate_*

 * moves the generic libblkid/libvolume_id wrapper (fsprobe.c) from
   mount/ to lib/. We'll use the wrapper in cfdisk and fsck.

   The wrapper supports:

    - obsolete volume_id (udev)
    - obsolete libblkid (e2fsprogs)
    - libblkid (util-linux-ng)

 * mount, umount and swapon when linked against the new libblkid use

    - low-level probing code to read LABEL, UUID or FSTYPE from a device
    - high-level blkid_evaluate_spec() to convert LABEL/UUID to devname

Signed-off-by: Karel Zak <kzak@redhat.com>