Merge remote-tracking branch 'remotes/berrange/tags/block-odirect-pull-request' into...

block: improve error reporting for unsupported O_DIRECT

# gpg: Signature made Wed 16 Sep 2020 10:45:48 BST
# gpg:                using RSA key DAF3A6FDB26B62912D0E8E3FBE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>" [full]
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>" [full]
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange/tags/block-odirect-pull-request:
  block/file: switch to use qemu_open/qemu_create for improved errors
  util: give a specific error message when O_DIRECT doesn't work
  util: introduce qemu_open and qemu_create with error reporting
  util: add Error object for qemu_open_internal error reporting
  util: refactor qemu_open_old to split off variadic args handling
  util: rename qemu_open() to qemu_open_old()
  util: split off a helper for dealing with O_CLOEXEC flag
  monitor: simplify functions for getting a dup'd fdset entry

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