Fix compile under Ubuntu 64bit

Some missing includes.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/history.cpp

@@ -23,6 +23,7 @@
 ////
 
 #include <cassert>
+#include <cstring>
 
 #include "history.h"
 

src/material.cpp

@@ -23,6 +23,7 @@
 ////
 
 #include <cassert>
+#include <cstring>
 #include <map>
 
 #include "material.h"

src/pawns.cpp

@@ -23,6 +23,7 @@
 ////
 
 #include <cassert>
+#include <cstring>
 
 #include "pawns.h"
 

src/square.h

@@ -25,6 +25,7 @@
 //// Includes
 ////
 
+#include <cstdlib> // for abs()
 #include <string>
 
 #include "color.h"

src/tt.cpp

@@ -24,6 +24,7 @@
 
 #include <cassert>
 #include <cmath>
+#include <cstring>
 
 #include "tt.h"