Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20181012' into staging

More s390x updates:
- introduce support for vfio-ap (s390 crypto devices), including a
  Linux headers update to get the new interfaces
- the usual fixing + cleanup

# gpg: Signature made Fri 12 Oct 2018 10:54:38 BST
# gpg:                using RSA key DECF6B93C6F02FAF
# gpg: Good signature from "Cornelia Huck <conny@cornelia-huck.de>"
# gpg:                 aka "Cornelia Huck <huckc@linux.vnet.ibm.com>"
# gpg:                 aka "Cornelia Huck <cornelia.huck@de.ibm.com>"
# gpg:                 aka "Cornelia Huck <cohuck@kernel.org>"
# gpg:                 aka "Cornelia Huck <cohuck@redhat.com>"
# Primary key fingerprint: C3D0 D66D C362 4FF6 A8C0  18CE DECF 6B93 C6F0 2FAF

* remotes/cohuck/tags/s390x-20181012:
  hw/s390x: Include the tod-qemu also for builds with --disable-tcg
  s390: doc: detailed specifications for AP virtualization
  s390x/vfio: ap: Introduce VFIO AP device
  s390x/ap: base Adjunct Processor (AP) object model
  s390x/kvm: enable AP instruction interpretation for guest
  s390x/cpumodel: Set up CPU model for AP device support
  linux-headers: update
  target/s390x/excp_helper: Remove DPRINTF() macro

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