block: include base when checking image chain for block allocation

block: include base when checking image chain for block allocation

This patch is used in the 'block/stream: introduce a bottom node'
that is following. Instead of the base node, the caller may pass
the node that has the base as its backing image to the function
bdrv_is_allocated_above() with a new parameter include_base = true
and get rid of the dependency on the base that may change during
commit/stream parallel jobs. Now, if the specified base is not
found in the backing image chain, the QEMU will abort.

Suggested-by: Vladimir Sementsov-Ogievskiy <[email protected]>
Signed-off-by: Andrey Shinkevich <[email protected]>
Reviewed-by: Vladimir Sementsov-Ogievskiy <[email protected]>
Reviewed-by: Alberto Garcia <[email protected]>
Message-id: 1559152576[email protected]
[mreitz: Squashed in the following as a rebase on conflicting patches:]
Message-id: e3cf99ae-62e9-8b6e-5a06-d3c8b9363b85@redhat.com
Signed-off-by: Max Reitz <[email protected]>