Fixed a bug in EventLoggerHelpers::LogTableFileCreation

Summary:
Fixed a missing "}" at the end of the generated JSON Log
in EventLoggerHelpers::LogTableFileCreation.

Test Plan: db_bench

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38919

db/event_logger_helpers.cc

@@ -53,6 +53,7 @@ void EventLoggerHelpers::LogTableFileCreation(
     }
     jwriter.EndObject();
   }
+  jwriter.EndObject();
 
   event_logger->Log(jwriter);
 }