Merge branch 'ab/refs-various-fixes'

Code clean-up.

* ab/refs-various-fixes:
  refs debug: add a wrapper for "read_symbolic_ref"
  packed-backend: remove stub BUG(...) functions
  misc *.c: use designated initializers for struct assignments
  refs: use designated initializers for "struct ref_iterator_vtable"
  refs: use designated initializers for "struct ref_storage_be"

attr.c

@@ -79,7 +79,7 @@ static int attr_hash_entry_cmp(const void *unused_cmp_data,
  * Access to this dictionary must be surrounded with a mutex.
  */
 static struct attr_hashmap g_attr_hashmap = {
-	HASHMAP_INIT(attr_hash_entry_cmp, NULL)
+	.map = HASHMAP_INIT(attr_hash_entry_cmp, NULL),
 };
 
 /*