[Libguestfs] [PATCH nbdkit 0/2] Temporarily remove .list_exports for nbdkit 1.22

If you're following nbdkit development upstream you'll have seen that we are still making changes to the .list_exports and related APIs. The current .list_exports API upstream is not how it will look finally. The latest set of proposals was here: https://www.redhat.com/archives/libguestfs/2020-August/thread.html#00330 At the same time I'd like to do an nbdkit 1.22 (stable) release. There are a few reasons for this, some good and some not so great: - We have sufficient new features and the schedule is right to do a release, but I don't want to push large changes in at the last minute. - The VDDK plugin has several vital fixes which will be appreciated by anyone using nbdkit to access VMware. - The Windows patches could be added _after_ we do the stable release so they have plenty of time to sit in development. At the moment I have to keep rebasing them. - (The not so good one) RHEL 8 demands that we either rebase nbdkit now, as in _today_, or else we will wait for many months before our customers can use the new features. Therefore I propose the two following patches. The first one removes the mention of list_exports and nbdkit*export* APIs from the 1.22 release notes. The second one is for stable-1.22 only (before 1.22.0 goes out). It removes the .list_exports feature from plugins. It also removes the nbdkit*export* APIs from <nbdkit-plugin.h> (ie. the public API). This doesn't affect development, it would only be for the 1.22 release. Rich.