hdf5_der

Two minor cache changes:

* Evict-on-close behavior is now skipped when the file is closing.
  This fixes a potential issue discovered by Valgind on Windows
  where potentially garbage data would be availble for manipulation.

* Added brackets to some code in the tagged entry evict iterators
  so that the flag that determines if progress was made only gets
  set if things are actually evicted. This prevents an infinite
  loop (and emits an error) when pinned entries prevent eviction
  and thus progress.