Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging

# gpg: Signature made Mon 18 Dec 2017 21:05:53 GMT
# gpg:                using RSA key 0xBDBE7B27C0DE3057
# gpg: Good signature from "Jeffrey Cody <[email protected]>"
# gpg:                 aka "Jeffrey Cody <[email protected]>"
# gpg:                 aka "Jeffrey Cody <[email protected]>"
# Primary key fingerprint: 9957 4B4D 3474 90E7 9D98  D624 BDBE 7B27 C0DE 3057

* remotes/cody/tags/block-pull-request:
  block/curl: fix minor memory leaks
  block/curl: check error return of curl_global_init()
  block/sheepdog: code beautification
  block/sheepdog: remove spurious NULL check
  blockjob: kick jobs on set-speed
  backup: use copy_bitmap in incremental backup
  backup: simplify non-dirty bits progress processing
  backup: init copy_bitmap from sync_bitmap for incremental
  backup: move from done_bitmap to copy_bitmap
  hbitmap: add next_zero function

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