- Add missing include for the debug printout

git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@1201 3ecf2c5c-341e-0410-92b4-d18e462d057c

src/backend/concrete_history.cc

@@ -44,6 +44,10 @@
 #include <cassert>
 #include <functional>
 
+#ifndef NDEBUG
+#include <iostream>
+#endif
+
 using namespace sgpem;
 using namespace std;
 using memory::smart_ptr;