Linux 4.4: Use locks_lock_file_wait

Linux 4.4: Use locks_lock_file_wait

The locks API was changed in Linux 4.4, introducing locks_lock_file_wait
(e55c34a66f87e78fb1fc6b623b78c5ad74b475af) and removing
flock_lock_file_wait (616fb38fa7a9599293e05ae1fa9acfaf73922434).

locks_lock_file_wait can be used as a drop-in replacement so define
flock_lock_file_wait as an alias for it.

Change-Id: Iba89a43c651737c86cbf519a933289d97c25a467
Reviewed-on: https://gerrit.openafs.org/12170
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>