pull: drop fetching_sync_uri

This made sense back when we used a main loop even when we needed to
fetch objects synchronously. Nowadays, we no longer actually update
progress before the FETCHING_OBJECTS phase, which is only for async
requests.

This allows us to get rid of fetch_uri_contents_membuf_sync() and to
generalize fetch_uri_contents_utf8_sync() so that it only requires a
fetcher. This will be needed later.

Closes: #469
Approved by: cgwalters

src/libostree/ostree-metalink.h

@@ -53,7 +53,6 @@ SoupURI *_ostree_metalink_get_uri (OstreeMetalink         *self);
 gboolean _ostree_metalink_request_sync (OstreeMetalink        *self,
                                         SoupURI               **out_target_uri,
                                         GBytes                **out_data,
-                                        SoupURI               **fetching_sync_uri,
                                         GCancellable          *cancellable,
                                         GError                **error);
 G_END_DECLS