Increase size of node_name

From: Tim Smith <tim.smith@citrix.com>

We need to be able to store longer node names so that we can
support encoding a UUID and a volume id which may be up to
8 bytes long. Though we base64 encode these to shorten them,
32 bytes of node_name is still not quite enough.
---
 include/block/block_int-common.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 8947abab76..4fb1c6acfc 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -1085,7 +1085,7 @@ struct BlockDriverState {
     unsigned int supported_truncate_flags;
 
     /* the following member gives a name to every node on the bs graph. */
-    char node_name[32];
+    char node_name[64];
     /* element of the list of named nodes building the graph */
     QTAILQ_ENTRY(BlockDriverState) node_list;
     /* element of the list of all BlockDriverStates (all_bdrv_states) */
