Merge remote-tracking branch 'remotes/armbru/tags/pull-tests-2018-08-16' into staging

Merge remote-tracking branch 'remotes/armbru/tags/pull-tests-2018-08-16' into staging

Testing patches for 2018-08-16

# gpg: Signature made Thu 16 Aug 2018 09:34:43 BST
# gpg:                using RSA key 3870B400EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-tests-2018-08-16: (25 commits)
  libqtest: Improve error reporting for bad read from QEMU
  tests/libqtest: Improve kill_qemu()
  libqtest: Rename qtest_FOOv() to qtest_vFOO() for consistency
  libqtest: Replace qtest_startf() by qtest_initf()
  libqtest: Enable compile-time format string checking
  migration-test: Clean up string interpolation into QMP, part 3
  migration-test: Clean up string interpolation into QMP, part 2
  migration-test: Clean up string interpolation into QMP, part 1
  migration-test: Make wait_command() cope with '%'
  tests: New helper qtest_qmp_receive_success()
  migration-test: Make wait_command() return the "return" member
  tests: Clean up string interpolation around qtest_qmp_device_add()
  cpu-plug-test: Don't pass integers as strings to device_add
  tests: Clean up string interpolation into QMP input (simple cases)
  tests: Pass literal format strings directly to qmp_FOO()
  qobject: qobject_from_jsonv() is dangerous, hide it away
  test-qobject-input-visitor: Avoid format string ambiguity
  libqtest: Simplify qmp_fd_vsend() a bit
  qobject: New qobject_from_vjsonf_nofail(), qdict_from_vjsonf_nofail()
  qobject: Replace qobject_from_jsonf() by qobject_from_jsonf_nofail()
  ...

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