fix with Boost 1.79

Index: src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp
--- src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp.orig
+++ src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp
@@ -36,6 +36,7 @@
 #include <limits>
 
 #include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
 #include <boost/filesystem/path.hpp>
 #include <pcrecpp.h>
 
