locking: put the Solaris share reservation after our locking stuff

Fix for Bug 560: put the Solaris share reservation after our locking stuff.
Note that this still leaves room for a race condition where between placing our own
locks above and putting the Solaris share move below another client puts a lock.
We then end up with set locks from above and return with an error code, the proper
fix requires a sane cleanup function for the error path in this function.

Signed-off-by: Ralph Boehme <rb@sernet.de>
Merge branch 'sharemodes-bug560' into branch-netatalk-3-1