lib/repo: Make ost_repo_remove_remote() available internally

Make it an internal, not static, API; like _ostree_repo_add_remote(). It
will be used in many the same situations.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Closes: #875
Approved by: cgwalters

src/libostree/ostree-repo-private.h

@@ -354,6 +354,9 @@ _ostree_repo_update_mtime (OstreeRepo        *self,
 gboolean
 _ostree_repo_add_remote (OstreeRepo   *self,
                          OstreeRemote *remote);
+gboolean
+_ostree_repo_remove_remote (OstreeRepo   *self,
+                            OstreeRemote *remote);
 OstreeRemote *
 _ostree_repo_get_remote (OstreeRepo  *self,
                          const char  *name,