journal/Entry: include <sstream> instead of <strstream>

The `strstream` header is obsolete.

Signed-off-by: Max Kellermann <[email protected]>

Author: MaxKellermann

src/journal/Entry.cc

@@ -5,7 +5,8 @@
 #include "include/encoding.h"
 #include "include/stringify.h"
 #include "common/Formatter.h"
-#include <strstream>
+
+#include <sstream>
 
 #define dout_subsys ceph_subsys_journaler
 #undef dout_prefix