On the fsfs-ucsnorm branch: Fix crashes in fs-test.

* subversion/libsvn_fs_fs/temp_serializer.c
  (serialize_dir_entry):
   Serialize a NULL key if it's the same as the entry name,
   not an empty string; and remove the now-unused local variable.
  (find_entry): If the entry key is NULL, use the dirent name
   as the comparison key.
  (deserialize_dir, svn_fs_fs__extract_dir_entry):
   Check only for a null entry key, not an empty string.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-ucsnorm@1562210 13f79535-47bb-0310-9956-ffa450edef68