MFC 306426

hyperv/storvsc: Fix the blkvsc disk attachment issues.

- The original 'disengage' ATA controller model does not work properly
for all possible disk configurations. Use the newly added ATA disk
veto eventhandler to fit into all possible disk configuration.
- If the 'invalid LUN' happens on blkvsc controllers, return
CAM_DEV_NOT_THERE so that CAM will not destroy attached disks under
the blkvsc controllers.

Submitted by: Hongjiang Zhang <honzhan microsoft com>
Discussed with: mav
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D7693

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Import Hyper-V paravirtualized drivers from projects/hyperv
branch into head.

Approved by: re@ (hrs)
Obtained from: Microsoft, NetApp, and Citrix.

Connect the stordisengage driver to the build.

make glue to hook up the hyperv kmods to the build.

Modified from the original Microsoft versions to pull
code/headers in from the sys/contrib/dev directory.