[libhandy] header-group: Specify null values in GMarkupParser

[Adrien Plazas <aplazas src gnome org>]

commit 163237b8a59a30917796d54484d2126b8645bc75
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Tue Feb 16 02:36:20 2021 +0500

    header-group: Specify null values in GMarkupParser
    
    Prevent warnings with -Wmissing-field-initializers.

 src/hdy-header-group.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/src/hdy-header-group.c b/src/hdy-header-group.c
index ce155df1..cb99c7ae 100644
--- a/src/hdy-header-group.c
+++ b/src/hdy-header-group.c
@@ -679,11 +679,11 @@ _gtk_builder_error_unhandled_tag (GtkBuilder           *builder,
 /* This has been copied and modified from gtksizegroup.c. */
 static void
 header_group_start_element (GMarkupParseContext  *context,
-                          const gchar          *element_name,
-                          const gchar         **names,
-                          const gchar         **values,
-                          gpointer              user_data,
-                          GError              **error)
+                            const gchar          *element_name,
+                            const gchar         **names,
+                            const gchar         **values,
+                            gpointer              user_data,
+                            GError              **error)
 {
   GSListSubParserData *data = (GSListSubParserData*)user_data;
 
@@ -730,7 +730,11 @@ header_group_start_element (GMarkupParseContext  *context,
 /* This has been copied and modified from gtksizegroup.c. */
 static const GMarkupParser header_group_parser =
   {
-    header_group_start_element
+    header_group_start_element,
+    NULL,
+    NULL,
+    NULL,
+    NULL
   };
 
 /* This has been copied and modified from gtksizegroup.c. */