block: Mark commit, mirror, blkreplay as filters

The commit, mirror, and blkreplay block nodes are filters, so they should
be marked as such.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200513110544.176672-2-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
3 files changed