ostree-repo: add new API to sign the summary file

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

src/libostree/ostree-repo.h

@@ -712,6 +712,13 @@ gboolean ostree_repo_sign_delta (OstreeRepo     *self,
                                  GCancellable   *cancellable,
                                  GError        **error);
 
+gboolean
+ostree_repo_add_gpg_signature_summary (OstreeRepo     *self,
+                                       const gchar    **key_id,
+                                       const gchar    *homedir,
+                                       GCancellable   *cancellable,
+                                       GError        **error);
+
 gboolean ostree_repo_append_gpg_signature (OstreeRepo     *self,
                                            const gchar    *commit_checksum,
                                            GBytes         *signature_bytes,