qemu-io: Switch 'map' output to byte-based reporting

Mixing byte offset and sector allocation counts is a bit
confusing.  Also, reporting n/m sectors, where m decreases
according to the remaining size of the file, isn't really
adding any useful information; and reporting an offset at
both the front and end of the line, with large amounts of
whitespace, is pointless.  Update the output to use byte
counts and shorter lines, then adjust the affected tests
(./check -qcow2 102, ./check -vpc 146).

Note that 'qemu-io map' is MUCH weaker than 'qemu-img map';
the former only shows which regions of the active layer are
allocated, without regards to where the allocation comes from
or whether the allocated portion is known to read as zero
(because it is using the weaker bdrv_is_allocated()); while the
latter (especially in --output=json mode) reports more details
from bdrv_get_block_status().

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170429191419.30051-4-eblake@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
