fix std::function usage

Martin Rotter · Martin Rotter · commit bc910d5098f0 · 2021-09-03T13:22:00.000+02:00
diff --git a/src/librssguard/gui/messagebox.h b/src/librssguard/gui/messagebox.h
@@ -6,6 +6,8 @@
 #include <QDialogButtonBox>
 #include <QMessageBox>
 
+#include <functional>
+
 class MessageBox : public QMessageBox {
   Q_OBJECT
 
