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.c

@@ -593,7 +593,6 @@ gboolean
 _ostree_metalink_request_sync (OstreeMetalink        *self,
                                SoupURI               **out_target_uri,
                                GBytes                **out_data,
-                               SoupURI               **fetching_sync_uri,
                                GCancellable          *cancellable,
                                GError                **error)
 {
@@ -604,9 +603,6 @@ _ostree_metalink_request_sync (OstreeMetalink        *self,
   gsize len;
   const guint8 *data;
 
-  if (fetching_sync_uri != NULL)
-    *fetching_sync_uri = _ostree_metalink_get_uri (self);
-
   mainctx = g_main_context_new ();
   g_main_context_push_thread_default (mainctx);