"check" is full of qemu-iotests--specific details.  Separating it
from "common" does not make much sense anymore.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>