fix ContentItemsSource.printStatistics to print only if verbose

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1200756 13f79535-47bb-0310-9956-ffa450edef68

modules/benchmark/src/java/org/apache/lucene/benchmark/byTask/feeds/ContentItemsSource.java

@@ -149,6 +149,9 @@ public abstract class ContentItemsSource {
   }
 
   public void printStatistics(String itemsName) {
+    if (!verbose) {
+      return;
+    }
     boolean print = false;
     String col = "                  ";
     StringBuilder sb = new StringBuilder();