Remove bracket in the json output of the print histogram function

packet-exchange/src/client.c

@@ -289,7 +289,7 @@ static void print_histograms() {
     printf("%s", (i + 1 < 2 ? "], " : "]"));
   }
 
-  printf(   "]]}]}\n");
+  printf(   "]}]}\n");
 }
 
 static void sigint_handler(int sig_num) {