Merge remote-tracking branch 'remotes/sstabellini/tags/xen-20170721-tag' into staging

Xen 2017/07/21

# gpg: Signature made Sat 22 Jul 2017 01:43:34 BST
# gpg:                using RSA key 0x894F8F4870E1AE90
# gpg: Good signature from "Stefano Stabellini <stefano.stabellini@eu.citrix.com>"
# gpg:                 aka "Stefano Stabellini <sstabellini@kernel.org>"
# Primary key fingerprint: D04E 33AB A51F 67BA 07D3  0AEA 894F 8F48 70E1 AE90

* remotes/sstabellini/tags/xen-20170721-tag:
  xen-mapcache: Fix the bug when overlapping emulated DMA operations may cause inconsistency in guest memory mappings
  xen: fix compilation on 32-bit hosts

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