lib: Define an alias OSTREE_REPO_MODE_ARCHIVE

For the old `OSTREE_REPO_MODE_ARCHIVE_Z2`.  Use it mostly tree
wide except for the repo finder tests (to avoid conflicting with
some outstanding PRs).

Just noted another user coming in some of those tests and wanted to do a
cleanup.

Closes: #1209
Approved by: jlebon

src/libostree/ostree-repo-pull.c

@@ -1029,7 +1029,7 @@ content_fetch_on_complete (GObject        *object,
    * the content rather than paying the cost of exploding it, checksumming, and
    * re-gzip.
    */
-  if (pull_data->is_mirror && pull_data->repo->mode == OSTREE_REPO_MODE_ARCHIVE_Z2
+  if (pull_data->is_mirror && pull_data->repo->mode == OSTREE_REPO_MODE_ARCHIVE
       && !pull_data->is_bareuseronly_files)
     {
       gboolean have_object;
@@ -3529,7 +3529,7 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
                                                 &pull_data->has_tombstone_commits, error))
         goto out;
 
-      if (pull_data->remote_mode != OSTREE_REPO_MODE_ARCHIVE_Z2)
+      if (pull_data->remote_mode != OSTREE_REPO_MODE_ARCHIVE)
         {
           g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                        "Can't pull from archives with mode \"%s\"",
@@ -3550,7 +3550,7 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
     }
 
   /* We can't use static deltas if pulling into an archive repo. */
-  if (self->mode == OSTREE_REPO_MODE_ARCHIVE_Z2)
+  if (self->mode == OSTREE_REPO_MODE_ARCHIVE)
     {
       if (pull_data->require_static_deltas)
         {
@@ -4894,7 +4894,7 @@ find_remotes_cb (GObject      *obj,
       if (commit_metadata->timestamp != 0)
         continue;
 
-      _ostree_loose_path (buf, commit_metadata->checksum, OSTREE_OBJECT_TYPE_COMMIT, OSTREE_REPO_MODE_ARCHIVE_Z2);
+      _ostree_loose_path (buf, commit_metadata->checksum, OSTREE_OBJECT_TYPE_COMMIT, OSTREE_REPO_MODE_ARCHIVE);
       commit_filename = g_build_filename ("objects", buf, NULL);
 
       /* For each of the remotes whose summary files contain this ref, try