[Libguestfs] [PATCH nbdkit v5 3/3] cache: Implement cache-max-size and cache space reclaim.

v4: https://www.redhat.com/archives/libguestfs/2019-January/msg00032.html v5: - Now we set the block size at run time. I'd like to say that I was able to test this change, but unfortunately I couldn't find any easy way to create a filesystem on x86-64 with a block size > 4K. Ext4 doesn't support it at all, and XFS doesn't support block size > page size (and I recently gave away my aarch64 machine that ran RHEL, so ..) - Addressed a few other minor issues that Eric found in v4. - Retested on Linux, FreeBSD and OpenBSD. I'm including the minmax patch which I sent before. That's because it isn't independent as I thought it was - it depends on the LRU patch. Rich.