Remove unused headers

Author: Ankit Gupta

java/rocksjni/statistics.cc

@@ -9,13 +9,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <jni.h>
-#include <string>
-#include <memory>
 
 #include "include/org_rocksdb_Statistics.h"
 #include "rocksjni/portal.h"
 #include "rocksdb/statistics.h"
-#include "rocksdb/options.h"
 
 /*
  * Class:     org_rocksdb_Statistics