Restore std::cout instead of printf()

I am not able to reproduce the speed regression anymore,
and also we were using cout even before speed regression
so probably the reason is not there.

No functional change.

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

src/main.cpp

@@ -17,7 +17,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <cstdio>
 #include <iostream>
 #include <string>
 
@@ -36,9 +35,6 @@ extern void kpk_bitbase_init();
 
 int main(int argc, char* argv[]) {
 
-  // Disable output buffering: printf() does not work correctly otherwise
-  setvbuf(stdout, NULL, _IONBF, 0);
-
   bitboards_init();
   Position::init();
   kpk_bitbase_init();