vchoi_fork

Make some changes to conserve filespace and ensure that all filespace is
eventually reclaimed.

Defer reclamation of raw data filespace, only.

XXX Deferring only raw-data reclamation isn't *quite* sufficient because
XXX a writer could conceivably reuse metadata space as raw-data space
XXX before max_lag ticks have elapsed.  Readers could see metadata
XXX corrupted by raw data.

Once a file starts to close, stop deferring reclamation.

In H5MF_free_aggrs(), perform all deferred reclamations if the file is
closing.