libmount: fix a mem leak

Signed-off-by: Karel Zak <kzak@redhat.com>
lslocks: add BLOCKER column

 BLOCKER -  PID of the process blocking the lock

Signed-off-by: Karel Zak <kzak@redhat.com>
lslocks: support -o +<list> convention

Signed-off-by: Karel Zak <kzak@redhat.com>
docs: add missing information about -o +<list>

Signed-off-by: Karel Zak <kzak@redhat.com>
lsblk: resuse udev handler

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