Merge remote-tracking branch 'remotes/thuth-gitlab/tags/pull-request-2021-03-21'...

* Small fixes for the unit tests
* Compilation fixes for Illumos et al.
* Update the FreeBSD VM to 12.2

# gpg: Signature made Sun 21 Mar 2021 16:51:42 GMT
# gpg:                using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5
# gpg:                issuer "thuth@redhat.com"
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg:                 aka "Thomas Huth <thuth@redhat.com>" [full]
# gpg:                 aka "Thomas Huth <huth@tuxfamily.org>" [full]
# gpg:                 aka "Thomas Huth <th.huth@posteo.de>" [unknown]
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3  EAB9 2ED9 D774 FE70 2DB5

* remotes/thuth-gitlab/tags/pull-request-2021-03-21:
  FreeBSD: Upgrade to 12.2 release
  contrib: ivshmem client and server build fix for SunOS.
  configure: fix for SunOS based systems
  tests/unit/test-block-iothread: fix maybe-uninitialized error on GCC 11
  docs/devel/testing.rst: Fix references to unit tests

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