Windows: Refactor AFSProcessSupport

Windows: Refactor AFSProcessSupport

Breakup AFSProcessNotify() into AFSProcessCreate() and
AFSProcessDestroy().

Correct inconsistencies with ETHREAD vs ThreadId HANDLE.

Add AFSProcessNotifyEx() and use PsSetCreateProcessNotifyRoutineEx()
to register it on Vista SP1 and above.

Change-Id: I2be85c3e8229883b4e239e1fdba9a65fc704daaa
Reviewed-on: http://gerrit.openafs.org/6926
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>