storage: Add virCheckFlags to virStorageBackendRBDDeleteVol

The initial commit '74951ead' did not include the proper check for whether
any flags are supported by the driver.

Even though the driver doesn't support VIR_STORAGE_VOL_DELETE_ZEROED,
it still checks and allows the processing to continue

Also add the new VIR_STORAGE_VOL_DELETE_WITH_SNAPSHOTS since it is handled
as of commit id '3c7590e0'.

src/storage/storage_backend_rbd.c

@@ -513,6 +513,9 @@ static int virStorageBackendRBDDeleteVol(virConnectPtr conn,
     ptr.cluster = NULL;
     ptr.ioctx = NULL;
 
+    virCheckFlags(VIR_STORAGE_VOL_DELETE_ZEROED |
+                  VIR_STORAGE_VOL_DELETE_WITH_SNAPSHOTS, -1);
+
     VIR_DEBUG("Removing RBD image %s/%s", pool->def->source.name, vol->name);
 
     if (flags & VIR_STORAGE_VOL_DELETE_ZEROED)