Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

virtio: fix for rc2

Looks like the constant stream of additions of vhost-user devices is a
problem for some people who are concerned about external connections
from qemu. A per-device flag seems like an overkill, but a single
configure flag seems like a sane way to support that, and it looks like
we need to do it before the release.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Thu 03 Aug 2017 13:57:57 BST
# gpg:                using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream:
  build-sys: add --disable-vhost-user

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>