Fix unsigned int flag in db_bench (#4129)

Summary:
`DEFINE_uint32` was unavailable on some platforms, e.g., https://travis-ci.org/facebook/rocksdb/jobs/403352902. Use `DEFINE_uint64` instead which should work as it's used many times elsewhere in this file.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4129

Differential Revision: D8830311

Pulled By: ajkr

fbshipit-source-id: b4fc90ba3f50e649c070ce8069c68e530d731f05

tools/db_bench_tool.cc

@@ -1028,7 +1028,7 @@ DEFINE_bool(identity_as_first_hash, false, "the first hash function of cuckoo "
             "table becomes an identity function. This is only valid when key "
             "is 8 bytes");
 DEFINE_bool(dump_malloc_stats, true, "Dump malloc stats in LOG ");
-DEFINE_uint32(stats_dump_period_sec, rocksdb::Options().stats_dump_period_sec,
+DEFINE_uint64(stats_dump_period_sec, rocksdb::Options().stats_dump_period_sec,
               "Gap between printing stats to log in seconds");
 
 enum RepFactory {
@@ -3369,7 +3369,8 @@ void VerifyDBFromDB(std::string& truth_db_name) {
     options.wal_dir = FLAGS_wal_dir;
     options.create_if_missing = !FLAGS_use_existing_db;
     options.dump_malloc_stats = FLAGS_dump_malloc_stats;
-    options.stats_dump_period_sec = FLAGS_stats_dump_period_sec;
+    options.stats_dump_period_sec =
+        static_cast<unsigned int>(FLAGS_stats_dump_period_sec);
 
     options.compression_opts.level = FLAGS_compression_level;
     options.compression_opts.max_dict_bytes = FLAGS_compression_max_dict_bytes;