fix with Boost 1.79

Index: src/mongo/db/storage/storage_repair_observer.cpp
--- src/mongo/db/storage/storage_repair_observer.cpp.orig
+++ src/mongo/db/storage/storage_repair_observer.cpp
@@ -41,6 +41,7 @@
 #include <sys/types.h>
 #endif
 
+#include <boost/filesystem/fstream.hpp>
 #include <boost/filesystem/path.hpp>
 
 #include "mongo/db/dbhelpers.h"
