[gnote] Fix insert timestamp addin

[Aurimas Černius <aurimasc src gnome org>]

commit 080d7c15fdd8bf67c138b4a5919642e786b4fa5d
Author: Aurimas Černius <aurisc4 gmail com>
Date:   Sun Jan 17 14:12:54 2021 +0200

    Fix insert timestamp addin

 src/addins/inserttimestamp/inserttimestampnoteaddin.cpp | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/addins/inserttimestamp/inserttimestampnoteaddin.cpp 
b/src/addins/inserttimestamp/inserttimestampnoteaddin.cpp
index 5c7ef4ba..829501d5 100644
--- a/src/addins/inserttimestamp/inserttimestampnoteaddin.cpp
+++ b/src/addins/inserttimestamp/inserttimestampnoteaddin.cpp
@@ -40,6 +40,9 @@ namespace inserttimestamp {
   }
 
 
+  Glib::ustring InsertTimestampNoteAddin::s_date_format;
+  sigc::connection InsertTimestampNoteAddin::s_on_format_setting_changed_cid;
+
   void InsertTimestampNoteAddin::initialize()
   {
   }