Fix a memory leak in consdiffmgr.c

Fixes bug 23139; bugfix on 0.3.1.1-alpha.

changes/bug23139

@@ -0,0 +1,3 @@
+  o Minor bugfixes (directory cache):
+    - Fix a memory leak in the code that recovers space in the consensus
+      directory cache. Fixes bug 23139; bugfix on 0.3.1.1-alpha.

src/or/consdiffmgr.c

@@ -1156,6 +1156,7 @@ consdiffmgr_ensure_space_for_files(int n)
     if (++n_marked >= n_to_remove)
       break;
   } SMARTLIST_FOREACH_END(ent);
+  smartlist_free(objects);
 
   consensus_cache_delete_pending(cache, 1);
   if (BUG(n_marked < n_to_remove))