Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2020-03-17' into staging

Error reporting patches for 2020-03-17

# gpg: Signature made Tue 17 Mar 2020 16:30:49 GMT
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-error-2020-03-17:
  hw/sd/ssi-sd: fix error handling in ssi_sd_realize
  xen-block: Use one Error * variable instead of two
  hw/misc/ivshmem: Use one Error * variable instead of two
  Use &error_abort instead of separate assert()

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