Output journal snapshot as a single transaction.

Timeline/Loggable.C

@@ -382,6 +382,8 @@ Loggable::snapshot( FILE *fp )
         return false;
     }
 
+    block_start();
+
     for ( int i = 0; i < _log_id; ++i )
     {
         const Loggable * l = _loggables[ i ];
@@ -390,6 +392,8 @@ Loggable::snapshot( FILE *fp )
             l->log_create();
     }
 
+    block_end();
+
     _fp = ofp;
 
     return true;