Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20170803' into staging

Queued misc tcg patches

# gpg: Signature made Thu 03 Aug 2017 19:07:18 BST
# gpg:                using RSA key 0xAD1270CC4DD0279B
# gpg: Good signature from "Richard Henderson <rth7680@gmail.com>"
# gpg:                 aka "Richard Henderson <rth@twiddle.net>"
# Primary key fingerprint: 9CB1 8DDA F8E8 49AD 2AFC  16A4 AD12 70CC 4DD0 279B

* remotes/rth/tags/pull-tcg-20170803:
  tcg: Increase minimum alignment from tcg_malloc to 8
  target/s390x: Fix CSST for 16-byte store
  tcg/arm: Fix runtime overalignment test

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