Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20180328' into staging

Fix muluh_i64 and mulsh_i64 flags

# gpg: Signature made Wed 28 Mar 2018 05:46:45 BST
# gpg:                using RSA key 64DF38E8AF7E215F
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>"
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-tcg-20180328:
  tcg: Mark muluh_i64 and mulsh_i64 as 64-bit ops

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