do not create Statistics object unnecessarily

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/history/FileHistoryCache.java

@@ -103,15 +103,15 @@ private void doFileHistory(String filename, List<HistoryEntry> historyEntries,
             Repository repository, File srcFile, File root, boolean renamed)
             throws HistoryException {
 
-        Statistics statRepoHist = new Statistics();
-
         File file = new File(root, filename);
         // Only store directory history for the top-level directory.
         if (file.isDirectory() && !filename.equals(repository.getDirectoryName())) {
             LOGGER.log(Level.FINE, "Not storing history cache for {0}: not top level directory", file);
             return;
         }
 
+        Statistics statRepoHist = new Statistics();
+
         /*
          * If the file was renamed (in the changesets that are being indexed),
          * its history is not stored in the historyEntries so it needs to be acquired