Windows: Enforce free space checks every 1MB

Instead of performing a free space (or quota) check on every extending
write, perform the check only when the file length is increased beyond
the next 1MB boundary.   The file server permits 1MB quota over runs
and issuing the volume status rpc to the file server is extremely
expensive.  Especially for append only applications that write just a few
bytes at a time.

Reviewed-on: http://gerrit.openafs.org/9555
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit eecf7a1372f8fcb01d73b628850b488414d9ca3a)

Change-Id: I3f7b0233189b6bdc2cb76580e3597438ae7e47f3
Reviewed-on: http://gerrit.openafs.org/9584
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Revert "Windows: Treat all cached writes as write-through"

This reverts commit 5130681fa2d4a35d3f0b578d92c5db1892fdfb18.

Reviewed-on: http://gerrit.openafs.org/9572
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 3e4daf06a6e18d1a151b7de0b76b1a1698bdc814)

Change-Id: I1642538cae4e5b95b7db9da81b9fe71284078a33
Reviewed-on: http://gerrit.openafs.org/9585
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>