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

virtio,pc features, fixes

New features:
    guest RAM buffer overrun mitigation
    RAM physical address gaps for memory hotplug
    (except refactoring which got some review comments)

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

# gpg: Signature made Fri 02 Oct 2015 15:04:56 BST using RSA key ID D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"

* remotes/mst/tags/for_upstream:
  vhost-user-test: fix predictable filename on tmpfs
  vhost-user-test: use tmpfs by default
  pc: memhp: force gaps between DIMM's GPA
  memhp: extend address auto assignment to support gaps
  vhost-user: unit test for new messages
  vhost-user-test: do not reinvent glib-compat.h
  virtio: Notice when the system doesn't support MSIx at all
  pc: Add a comment explaining why pc_compat_2_4() doesn't exist
  exec: allocate PROT_NONE pages on top of RAM
  oslib: allocate PROT_NONE pages on top of RAM
  oslib: rework anonimous RAM allocation
  virtio-net: correctly drop truncated packets
  virtio: introduce virtqueue_discard()
  virtio: introduce virtqueue_unmap_sg()

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