vchoi_fork

Merge pull request #172 in HDFFV/hdf5 from ~KOZIOL/hdf5:develop to develop

* commit 'ea4d18c3d9c3b6c77030abdf2f0509bc68224559':
  Remove unnecessary assert.
  Add a flag for H5C__flush_single_entry() to allow the parallel code to request that images for entries be generated, even when not writing the entry from an MPI rank.