Linux-5.17: kernel func complete_and_exit renamed

Linux-5.17: kernel func complete_and_exit renamed

Handle the Linux kernel function rename made in commit
 "exit: Rename complete_and_exit to kthread_complete_and_exit"
 (cead1855)

Add a new autoconf test for the linux function kthread_complete_and_exit
and if not found use a define to map kthread_complete_and_exit to
complete_and_exit.

Replace calls to complete_and_exit with kthread_complete_and_exit.

Change-Id: If8db2d0abb1de8b08f511e9ff67612ef605cd603
Reviewed-on: https://gerrit.openafs.org/14882
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>