storage: volume_snapshot: add $running param

This add a $running param to volume_snapshot,
it can be used if some extra actions need to be done at the storage
layer when the snapshot has already be done at qemu level.

Signed-off-by: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>

src/PVE/Storage/ISCSIDirectPlugin.pm

@@ -232,7 +232,7 @@ sub volume_resize {
 }
 
 sub volume_snapshot {
-    my ($class, $scfg, $storeid, $volname, $snap) = @_;
+    my ($class, $scfg, $storeid, $volname, $snap, $running) = @_;
     die "volume snapshot is not possible on iscsi device\n";
 }