fix to allow compiling with g++ 4.5.1

Author: nouiz

plearn/io/PStreamBuf.h

@@ -40,6 +40,7 @@
 #ifndef PStreamBuf_INC
 #define PStreamBuf_INC
 
+#include <cstdio> //Needed by g++ 4.5.1 
 #include <plearn/base/PP.h>
 
 namespace PLearn {

plearn/io/pl_io.h

@@ -48,6 +48,7 @@
 #ifndef pl_io_INC
 #define pl_io_INC
 
+#include <cstdio> // needed by g++ 4.5.1
 #include <iostream>
 #include <map>
 #include <plearn/math/pl_math.h>        //!< For 'real'.

plearn/io/pl_nullstreambuf.h

@@ -41,6 +41,7 @@
 #else
 #  include <streambuf>
 #endif
+#include <cstdio> //Needed by g++ 4.5.1 
 
 namespace PLearn {
 using namespace std;

plearn/io/pl_streambuf.h

@@ -45,6 +45,7 @@
 
 //#include <iosfwd>
 #include <iostream>
+#include <cstdio> //Needed by g++ 4.5.1
 //#include "plerror.h"
 #include <plearn/base/PP.h>