Linux CM: Update wait code

Linux CM: Update wait code

Update the wait code to use the more modern wait_event_freezable()
macros. If those macros are not available, fall back to the older
wait_event_interruptible macro, and build our own
wait_event_freezable on top of this.

These changes should simplify our interactions with the wait queue
and refrigerator bits of the kernel, as we're now using more standard
interfaces to them.

Change-Id: I5218c8a1b5b33f10355ef298008c53e416b267f9
Reviewed-on: http://gerrit.openafs.org/4753
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>