Copy stable/11@r303970 to releng/11.0 as part of the 11.0-RELEASE
cycle.

Prune svn:mergeinfo from the new branch, and rename it to RC1.

Update __FreeBSD_version.

Use the quarterly branch for the default FreeBSD.conf pkg(8) repo and
the dvd1.iso packages population.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

The size of the first level reference count table is given in terms of the
number of clusters it occupies. It's not the number of entries in the table,
as it is for the L1 cluster table.

For small images, the two are the same. With the unit tests based on small
images, this change has therefore no effect on the unit test. For larger
images (like the FreeBSD 10.1-RELEASE image), this gives a discrepancy that
actually shows up when running "qemu-img check".

Bump the version number of mkimg.

While here, fix a white-space bug.

MFC after: 1 week

Finish QCOW version 2 and stop making it conditional.

We have a different ordering for the RC block(s) and L2 tables.
This is expected to be a non-issue, because everything is found
through file offsets in the corresponding RC table and L1 table.
Files that grow organically have RC blocks and L2 tables scattered
all over the place anyway.

The reason for the difference is that mkimg needs to be able to
write to a pipe. We can't seek forward and backward to fill in
the bits in non-sequential order.

Fix the creation of the L2 cluster table for version 1. The blkofs
variable was assigned the image offset in bytes and not in blocks
(i.e. sectors). This had image_data() return FALSE, which meant that
we didn't assign a cluster when we needed and also meant that we
didn't write parts of the L2 table when we should have. The result
being that the actual data clusters were written at the wrong offset.

Improve support for QCOW version 2. We're having the right layout
and even know how many refcnt blocks we need. All we need to do is
populate the refcnt blocks for every cluster we write and allocate
a cluster when we need a new refcnt block. The allocation part is
tricky in that it'll interleave with the assignment of clusters to
L2 tables and data. Since version 2 is not quite done, keep it
compiled out for now.

Add support for QCOW version 1. Version 2 is partially implemented.
And because of that, it's entirely disabled for now. Both versions
are similar enough that a single header definition works for both
of them. The only "diverting" side-effect is that the union of the
two is larger than the official V1 header.

What this means for our V1 support is that we can't put the L1 table
adjacent to the V1 header (i.e. at offset 0x30 in the file), unless
we revert to hackery and klugery. Let's not. Instead, we align the L1
table at the cluster boundary. This is in line with the V2 layout and
perfectly ok for V1 anyway (ok -- as far as I've seen so far).
Due to the alignment, our V1 image seems to be 1 cluster larger than
the V1 image created by qemu-img (on average).

Compression of the clusters is not supported at this time.

MFC after: 2 months