Fix tests under GCC_481

Summary:
This fix the issue with tests failing under GCC 481, I am not sure what is the exact reason
Closes https://github.com/facebook/rocksdb/pull/1735

Differential Revision: D4374094

Pulled By: IslamAbdelRahman

fbshipit-source-id: b3625bc

db/db_test_util.h

@@ -833,10 +833,10 @@ class DBTestBase : public testing::Test {
 
   std::vector<std::uint64_t> ListTableFiles(Env* env, const std::string& path);
 
-  void VerifyDBFromMap(std::map<std::string, std::string> true_data,
+  void VerifyDBFromMap(
-                       size_t* total_reads_res = nullptr,
+      std::map<std::string, std::string> true_data,
-                       bool tailing_iter = false,
+      size_t* total_reads_res = nullptr, bool tailing_iter = false,
-                       std::map<std::string, Status> status = {});
+      std::map<std::string, Status> status = std::map<std::string, Status>());
 
   void VerifyDBInternal(
       std::vector<std::pair<std::string, std::string>> true_data);