[libvirt] PATCH: Fix non-raw storage volume cloning

[Cole Robinson]

Daniel P. Berrange wrote:
> The recent storage patches broke cloning of non-raw volumes, due to a 
> small typo. THis was identified by the libvirt TCK storage tests!
> 

Go automated testing! ACK from me.

- Cole

> Daniel
> 
> diff --git a/src/storage_backend.c b/src/storage_backend.c
> index 1664804..67815d7 100644
> --- a/src/storage_backend.c
> +++ b/src/storage_backend.c
> @@ -567,7 +567,7 @@ virStorageBackendGetBuildVolFromFunction(virConnectPtr conn,
>          (inputvol->type == VIR_STORAGE_VOL_FILE &&
>           inputvol->target.format != VIR_STORAGE_VOL_FILE_RAW)) {
>  
> -        if ((tool_type = virStorageBackendFindFSImageTool(NULL)) != -1) {
> +        if ((tool_type = virStorageBackendFindFSImageTool(NULL)) < 0) {
>              virStorageReportError(conn, VIR_ERR_INTERNAL_ERROR,
>                                    "%s", _("creation of non-raw file images is "
>                                            "not supported without qemu-img."));
>