lib/repo-refs: Add a flag to exclude listing from refs/mirrors

Currently the flag OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES for
ostree_repo_list_collection_refs() means that refs in refs/remotes/
should be excluded but refs in refs/mirrors/ should still be checked, in
addition to refs/heads/ which is always checked. However in some
situations you want to exclude both remote and mirrored refs and only
check local "owned" ones. So this
commit adds a new flag OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_MIRRORS which
lets you exclude refs/mirrors/ from the listing.

This way we can avoid breaking API but still allow the listing of local
collection-refs.

The impetus for this change is that I'm changing Flatpak to make more
use of refs/mirrors, and we need a way to specify that a collection-ref
is local when using ostree_repo_resolve_collection_ref() in, for
example, the implementation of the repo command. The subsequent commit
will make the changes needed there.

Closes: #1825
Approved by: jlebon

src/libostree/ostree-repo.h

@@ -499,11 +499,13 @@ gboolean      ostree_repo_list_refs (OstreeRepo       *self,
  * @OSTREE_REPO_LIST_REFS_EXT_NONE: No flags.
  * @OSTREE_REPO_LIST_REFS_EXT_ALIASES: Only list aliases.  Since: 2017.10
  * @OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES: Exclude remote refs.  Since: 2017.11
+ * @OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_MIRRORS: Exclude mirrored refs.  Since: 2019.2
  */
 typedef enum {
   OSTREE_REPO_LIST_REFS_EXT_NONE = 0,
   OSTREE_REPO_LIST_REFS_EXT_ALIASES = (1 << 0),
   OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_REMOTES = (1 << 1),
+  OSTREE_REPO_LIST_REFS_EXT_EXCLUDE_MIRRORS = (1 << 2),
 } OstreeRepoListRefsExtFlags;
 
 _OSTREE_PUBLIC