Fix LITE Build (#4989)

Summary:
LITE mode has EventListener to be an empty class. However in db_bench,
it is used. When "override" is added to the functions, the build breaks. Fix it
by keeping the listener empty in LITE mode.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4989

Differential Revision: D14108132

Pulled By: siying

fbshipit-source-id: 80121aab35b1120e502b37b782301dd700692697

tools/db_bench_tool.cc

@@ -2044,6 +2044,7 @@ class Benchmark {
 
   class ErrorHandlerListener : public EventListener {
    public:
+#ifndef ROCKSDB_LITE
     ErrorHandlerListener()
         : mutex_(),
           cv_(&mutex_),
@@ -2085,6 +2086,10 @@ class Benchmark {
     InstrumentedCondVar cv_;
     bool no_auto_recovery_;
     bool recovery_complete_;
+#else   // ROCKSDB_LITE
+    bool WaitForRecovery(uint64_t /*abs_time_us*/) { return true; }
+    void EnableAutoRecovery(bool /*enable*/) {}
+#endif  // ROCKSDB_LITE
   };
 
   std::shared_ptr<ErrorHandlerListener> listener_;