[Libguestfs] [PATCH libnbd v2 0/3] Implement OClosures.

[Richard W.M. Jones]

v1 was here:
https://www.redhat.com/archives/libguestfs/2019-August/msg00168.html

I pushed uncontroversial patches 1-4

v2:

- The implementation of OClosure (new patch 1) in Python is fixed.

- Patch 2 (old patch 5) is unchanged.

- I added a new API for removing debug callbacks.  I think this
  approach has some advantages over using OClosure.

- I didn't yet do any work on changing the aio_*_callback
  functions to aio_*.

Rich.