common/Graylog: add missing include

MaxKellermann · MaxKellermann · commit 24c2b1994aa3 · 2024-11-04T22:31:05.000+01:00
Signed-off-by: Max Kellermann &lt;max.kellermann@ionos.com&gt;
diff --git a/src/common/Graylog.cc b/src/common/Graylog.cc
@@ -2,6 +2,9 @@
 // vim: ts=8 sw=2 smarttab
 
 #include "Graylog.h"
+
+#include <iostream> // for std::cerr
+
 #include "common/Formatter.h"
 #include "common/LogEntry.h"
 #include "log/Entry.h"
