xenstore: bump TDB_VERSION

Commit 9e49dcf67f ("xenstore: add per-node generation counter) changed
the TDB layout, which - in order to not break older xenstored running
on the same system - need to be accompanied by a version bump.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/tools/xenstore/tdb.c
+++ b/tools/xenstore/tdb.c
@@ -54,7 +54,7 @@
 #endif
 
 #define TDB_MAGIC_FOOD "TDB file\n"
-#define TDB_VERSION (0x26011967 + 6)
+#define TDB_VERSION (0x26011967 + 7)
 #define TDB_MAGIC (0x26011999U)
 #define TDB_FREE_MAGIC (~TDB_MAGIC)
 #define TDB_DEAD_MAGIC (0xFEE1DEAD)