Initial basic static delta code drop

This has a very basic level of functionality (deltas can be generated,
and applied offline).  There is only some stubbed out pull code to
fetch them via HTTP.

But, better to commit this now and improve it from a known starting
point, rather than have it languish in a branch.

src/libostree/ostree-repo.h

@@ -426,6 +426,37 @@ gboolean ostree_repo_list_objects (OstreeRepo                  *self,
                                    GCancellable                *cancellable,
                                    GError                     **error);
 
+gboolean ostree_repo_list_static_delta_names (OstreeRepo                  *self,
+                                              GPtrArray                  **out_deltas,
+                                              GCancellable                *cancellable,
+                                              GError                     **error);
+
+/**
+ * OstreeStaticDeltaGenerateOpt:
+ * @OSTREE_STATIC_DELTA_GENERATE_OPT_LOWLATENCY: Optimize for speed of delta creation over space
+ * @OSTREE_STATIC_DELTA_GENERATE_OPT_MAJOR: Optimize for delta size (may be very slow)
+ *
+ * Parameters controlling optimization of static deltas.
+ */
+typedef enum {
+  OSTREE_STATIC_DELTA_GENERATE_OPT_LOWLATENCY,
+  OSTREE_STATIC_DELTA_GENERATE_OPT_MAJOR
+} OstreeStaticDeltaGenerateOpt;
+
+gboolean ostree_repo_static_delta_generate (OstreeRepo                   *self,
+                                            OstreeStaticDeltaGenerateOpt  opt,
+                                            const char                   *from,
+                                            const char                   *to,
+                                            GVariant                     *metadata,
+                                            GCancellable                 *cancellable,
+                                            GError                      **error);
+
+gboolean ostree_repo_static_delta_execute_offline (OstreeRepo                    *self,
+                                                   GFile                         *dir,
+                                                   gboolean                       skip_validation,
+                                                   GCancellable                  *cancellable,
+                                                   GError                      **error);
+
 GHashTable *ostree_repo_traverse_new_reachable (void);
 
 gboolean ostree_repo_traverse_commit (OstreeRepo         *repo,