Change to handle as LOCK is not suuported for the case response of LOCK is
unimplemented.
Then
* LOCKSUPPORT == FALSE: LOCK is not suuported
* LOCKSUPPORT == TRUE: LOCK is supported
* lock == 0: no LOCK error
* lock == -1: failed to LOCK
Signed-off-by: OBATA Akio <obache@wizdas.com>
(cherry picked from commit b03db89643)