Merge remote-tracking branch 'kwolf/for-anthony' into staging

Merge remote-tracking branch 'kwolf/for-anthony' into staging

# By Kevin Wolf (12) and Peter Lieven (2)
# Via Kevin Wolf
* kwolf/for-anthony:
  nbd: Check against invalid option combinations
  nbd: Use default port if only host is specified
  block: Allow omitting the file name when using driver-specific options
  block: Make find_image_format safe with NULL filename
  block: Rename variable to avoid shadowing
  block: Introduce .bdrv_parse_filename callback
  nbd: Accept -drive options for the network connection
  nbd: Remove unused functions
  nbd: Keep hostname and port separate
  qemu-socket: Make socket_optslist public
  block: Pass bdrv_file_open() options to block drivers
  block: Add options QDict to bdrv_file_open() prototypes
  block: complete all IOs before resizing a device
  Revert "block: complete all IOs before .bdrv_truncate"