Ruediger Meier observed a regression with the PREVENT ALLOW
MEDIUM REMOVAL command in lk 3.19:
   http://www.spinics.net/lists/util-linux-ng/msg11448.html

Inspection indicated the same regression with VERIFY(10).

The patch is against lk 3.19.3 and also works with lk 4.0.0-rc6.
With this patch both commands are accepted and do nothing.
VERIFY(10) could be implemented since it shares logic with
COMPARE AND WRITE which is implemented; however that would
be an enhancement.

ChangeLog:
   - fix the lk 3.19 regression so that the PREVENT ALLOW
     MEDIUM REMOVAL command is supported once again
   - same fix for VERIFY(10)

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>