hdf5_chunking_query_bmr

[svn-r17006] Description:
	Bring r17005 from revise_chunks branch to trunk:

	Correct error in unpinning an entry from outside the cache to correctly
unpin the entry only when it is not being used for a flush dependency relation.

Tested on:
	FreeBSD/32 6.3 (duty)
	h5committested on branch