Close messageserver lock fd if lock can't be acquired.

Close messageserver lock fd directly without attempting to unlock
the file first, since close also releases any existent locks.

Change-Id: I7eb2945f82b95f3ed6d2ac2268d05c9737afa5cd
Signed-off-by: Valerio Valerio <valerio.valerio@jollamobile.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>