Windows: Mark Irp Pending before Deferring

After CcDeferWrite() is called we no longer have access to the
current Irp.  If we mark it deferred after calling CcDeferWrite()
we might mark the wrong thing.

Reviewed-on: http://gerrit.openafs.org/10684
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit d5bcff7429dd9972b17055a9abd98f3a590dee68)

Change-Id: I3ad55fe0ea24bc44b94d5f356ef4f927c9bf1d1d
Reviewed-on: http://gerrit.openafs.org/10691
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Windows: AFSCommonWrite STATUS_PENDING is Success

AFSCommonWrite() can return STATUS_PENDING if the write has been
deferred.  In that case, the function exit must not:

 * Update the Valid Data Length

 * Purge the cache

 * or do anything else related to the request

Reviewed-on: http://gerrit.openafs.org/10685
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 2d5f0a971baa05fc1a79726265a8235a0ebca4c0)

Change-Id: I001fc3f4dc53df705ca93b7014aff59de8b17ffb
Reviewed-on: http://gerrit.openafs.org/10692
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>