Applied patch from Dan Fandrich.

Thanks to Dan Fandrich.
I modified some lines to suite my taste.

src/ConsoleStatCalc.h

@@ -38,6 +38,7 @@
 #include "StatCalc.h"
 
 #include <string>
+#include <functional>
 
 #include "TimerA2.h"
 

src/DHTEntryPointNameResolveCommand.h

@@ -40,6 +40,7 @@
 #include <utility>
 #include <vector>
 #include <deque>
+#include <string>
 
 #include "SharedHandle.h"
 

src/DHTMessageReceiver.h

@@ -36,6 +36,9 @@
 #define D_DHT_MESSAGE_RECEIVER_H
 
 #include "common.h"
+
+#include <string>
+
 #include "SharedHandle.h"
 
 namespace aria2 {

src/DHTPeerAnnounceStorage.h

@@ -39,6 +39,7 @@
 
 #include <deque>
 #include <vector>
+#include <string>
 
 #include "SharedHandle.h"
 

src/DefaultPeerStorage.h

@@ -37,6 +37,7 @@
 
 #include "PeerStorage.h"
 
+#include <string>
 #include <map>
 
 #include "TimerA2.h"

src/DiskWriterFactory.h

@@ -36,6 +36,9 @@
 #define D_DISK_WRITER_FACTORY_H
 
 #include "common.h"
+
+#include <string>
+
 #include "SharedHandle.h"
 
 namespace aria2 {

src/IteratableChunkChecksumValidator.h

@@ -37,6 +37,8 @@
 
 #include "IteratableValidator.h"
 
+#include <string>
+
 namespace aria2 {
 
 class DownloadContext;

src/Logger.cc

@@ -35,6 +35,7 @@
 #include "Logger.h"
 
 #include <cstring>
+#include <cstdio>
 #include <iostream>
 
 #include "DlAbortEx.h"

src/Metalinker.cc

@@ -35,6 +35,7 @@
 #include "Metalinker.h"
 #include "MetalinkEntry.h"
 #include <algorithm>
+#include <functional>
 
 namespace aria2 {
 

src/OptionHandler.h

@@ -40,6 +40,7 @@
 #include <string>
 #include <vector>
 #include <iosfwd>
+#include <functional>
 
 #include "SharedHandle.h"
 

src/ParameterizedStringParser.h

@@ -36,6 +36,9 @@
 #define D_PARAMETERIZED_STRING_PARSER_H
 
 #include "common.h"
+
+#include <string>
+
 #include "PStringDatum.h"
 
 namespace aria2 {

src/RequestGroupMan.cc

@@ -42,6 +42,7 @@
 #include <fstream>
 #include <numeric>
 #include <algorithm>
+#include <utility>
 
 #include "BtProgressInfoFile.h"
 #include "RecoverableException.h"

src/TrackerWatcherCommand.h

@@ -36,6 +36,9 @@
 #define D_TRACKER_WATCHER_COMMAND_H
 
 #include "Command.h"
+
+#include <string>
+
 #include "SharedHandle.h"
 
 namespace aria2 {