Fix some lint warnings

db/version_edit.h

@@ -11,6 +11,7 @@
 #include <set>
 #include <utility>
 #include <vector>
+#include <string>
 #include "db/dbformat.h"
 
 namespace rocksdb {

db/version_set.cc

@@ -11,6 +11,7 @@
 
 #include <algorithm>
 #include <map>
+#include <set>
 #include <climits>
 #include <stdio.h>
 #include "db/filename.h"

include/rocksdb/column_family.h

@@ -8,6 +8,7 @@
 
 #pragma once
 #include "rocksdb/slice.h"
+#include <string>
 
 namespace rocksdb {
 
@@ -21,11 +22,10 @@ struct ColumnFamilyHandle {
   uint32_t id;
   // default
   ColumnFamilyHandle() : id() {}
-  /* implicit */
-  ColumnFamilyHandle(uint32_t _id) : id(_id) {}
+  explicit ColumnFamilyHandle(uint32_t _id) : id(_id) {}
 };
 
 const ColumnFamilyHandle default_column_family = ColumnFamilyHandle();
 extern const std::string default_column_family_name;
 
-}
+}  // namespace rocksdb