Windows: Direct IO for AFS Redirector

Windows: Direct IO for AFS Redirector

Implement a new IO processing model in which extents are not passed between
afsredirlib.sys and afsd_service.exe.  Instead the AFSCache file is
maintained exclusively by the service and the redirector locks kernel
memory, maps it into the service's address space, and permits the service
to manage all IO directly.

This interface adds an AFS Cache Bypass option to the AFS Redirector which
is activated when the file handle has been opened with the no intermediate
buffering option.

This patchset implements the kernel interface.  A subsequent
patchset will implement the service component.

Assisted by Jeffrey Altman <jaltman@your-file-system.com>

Change-Id: I25a4764db060b3b3f2b0de4006479dd3a220c6eb
Reviewed-on: http://gerrit.openafs.org/9210
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>