Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2020-07-07-v2' into staging

Error reporting patches patches for 2020-07-07

# gpg: Signature made Fri 10 Jul 2020 14:24:42 BST
# 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-2020-07-07-v2: (53 commits)
  xen: Use ERRP_GUARD()
  nbd: Use ERRP_GUARD()
  virtio-9p: Use ERRP_GUARD()
  fw_cfg: Use ERRP_GUARD()
  pflash: Use ERRP_GUARD()
  sd: Use ERRP_GUARD()
  scripts: Coccinelle script to use ERRP_GUARD()
  error: New macro ERRP_GUARD()
  hmp: Ignore Error objects where the return value suffices
  qdev: Ignore Error objects where the return value suffices
  qemu-img: Ignore Error objects where the return value suffices
  error: Avoid error_propagate() after migrate_add_blocker()
  qapi: Purge error_propagate() from QAPI core
  qapi: Smooth visitor error checking in generated code
  qapi: Smooth another visitor error checking pattern
  block/parallels: Simplify parallels_open() after previous commit
  error: Reduce unnecessary error propagation
  error: Eliminate error_propagate() manually
  error: Eliminate error_propagate() with Coccinelle, part 2
  error: Eliminate error_propagate() with Coccinelle, part 1
  ...

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