Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2016-06-20' into staging

Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2016-06-20' into staging

Error reporting patches for 2016-06-20

# gpg: Signature made Mon 20 Jun 2016 15:56:15 BST
# gpg:                using RSA key 0x3870B400EB918653
# gpg: Good signature from "Markus Armbruster <[email protected]>"
# gpg:                 aka "Markus Armbruster <[email protected]>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-error-2016-06-20:
  log: Fix qemu_set_log_filename() error handling
  log: Fix qemu_set_dfilter_ranges() error reporting
  log: Plug memory leak on multiple -dfilter
  coccinelle: Remove unnecessary variables for function return value
  error: Remove unnecessary local_err variables
  error: Remove NULL checks on error_propagate() calls
  vl: Error messages need to go to stderr, fix some

Signed-off-by: Peter Maydell <[email protected]>