common/Journald: add missing include

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

Author: MaxKellermann

src/common/Journald.cc

@@ -14,6 +14,9 @@
 #include <sys/un.h>
 #include <syslog.h>
 #include <unistd.h>
+
+#include <iostream> // for std::cerr
+
 #include <fmt/format.h>
 #include <fmt/ostream.h>
 
@@ -23,7 +26,6 @@
 #include "log/SubsystemMap.h"
 #include "msg/msg_fmt.h"
 
-
 namespace ceph::logging {
 
 namespace {