Add missing GType to flags in .gir

Here is a sample diff by this change:

--- Secret-1.gir.before	2019-05-07 15:20:58.252288010 +0900
+++ Secret-1.gir.after	2019-05-07 15:26:54.314413832 +0900
@@ -1141,22 +1140,32 @@
       </field>
     </record>
     <bitfield name="CollectionCreateFlags"
+              glib:type-name="SecretCollectionCreateFlags"
+              glib:get-type="secret_collection_create_flags_get_type"
               c:type="SecretCollectionCreateFlags">
       <doc xml:space="preserve">Flags for secret_collection_create().</doc>
-      <member name="collection_create_none"
+      <member name="none"
               value="0"
-              c:identifier="SECRET_COLLECTION_CREATE_NONE">
+              c:identifier="SECRET_COLLECTION_CREATE_NONE"
+              glib:nick="none">
         <doc xml:space="preserve">no flags</doc>
       </member>
     </bitfield>

Other flags such as SecretServiceFlags also have GType in .gir.