Merge remote-tracking branch 'remotes/xtensa/tags/20180409-xtensa' into staging

Fix file offset for preadv/pwritev linux-user syscalls.

# gpg: Signature made Tue 10 Apr 2018 03:04:24 BST
# gpg:                using RSA key 51F9CC91F83FA044
# gpg: Good signature from "Max Filippov <filippov@cadence.com>"
# gpg:                 aka "Max Filippov <max.filippov@cogentembedded.com>"
# gpg:                 aka "Max Filippov <jcmvbkbc@gmail.com>"
# Primary key fingerprint: 2B67 854B 98E5 327D CDEB  17D8 51F9 CC91 F83F A044

* remotes/xtensa/tags/20180409-xtensa:
  linux-user: fix preadv/pwritev offsets

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