Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.11-20171205' into staging

Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.11-20171205' into staging

ppc patch queue 2017-12-05

Alas, this is yet another fix for ppc that I think it's worth
squeezing into 2.11.  It's a really ugly fix for some pretty ugly
code, but it does seem to address a real problem.  It's also a problem
that's appeared relatively recently, since it was either created by,
or made much easier to trigger by, by the merge of MTTCG.

# gpg: Signature made Tue 05 Dec 2017 05:24:04 GMT
# gpg:                using RSA key 0x6C38CACA20D9B392
# gpg: Good signature from "David Gibson <david@gibson.dropbear.id.au>"
# gpg:                 aka "David Gibson (Red Hat) <dgibson@redhat.com>"
# gpg:                 aka "David Gibson (ozlabs.org) <dgibson@ozlabs.org>"
# gpg:                 aka "David Gibson (kernel.org) <dwg@kernel.org>"
# Primary key fingerprint: 75F4 6586 AE61 A66C C44E  87DC 6C38 CACA 20D9 B392

* remotes/dgibson/tags/ppc-for-2.11-20171205:
  target/ppc: Fix system lockups caused by interrupt_request state corruption

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