Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches:

- file-posix: Don't waste a file descriptor for locking, don't lock the
  same bit multiple times
- nvme: Fix double free and memory leak
- Misc error handling fixes
- Added NULL checks found by static analysis
- Allow more block drivers to not be included in the qemu build

# gpg: Signature made Mon 12 Nov 2018 17:05:00 GMT
# gpg:                using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  qcow2: Read outside array bounds in qcow2_pre_write_overlap_check()
  block: Fix potential Null pointer dereferences in vvfat.c
  qemu-img: assert block_job_get() does not return NULL in img_commit()
  block: Null pointer dereference in blk_root_get_parent_desc()
  job: Fix off-by-one assert checks for JobSTT and JobVerbTable
  block: Make more block drivers compile-time configurable
  tests: Add unit tests for image locking
  file-posix: Drop s->lock_fd
  file-posix: Skip effectiveless OFD lock operations
  nvme: free cmbuf in nvme_exit
  nvme: don't unref ctrl_mem when device unrealized
  blockdev: Consistently use snapshot_node_name in external_snapshot_prepare()
  blockdev: handle error on block latency histogram set error
  file-posix: Use error API properly

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