hdf5_chunking_query_bmr

[svn-r16536] Description:
	Bring v16532 back from trunk to v1.8 branch:

	Pass the chunk "user data" to H5D_chunk_unlock(), so that chunks with
an address already aren't reallocated.

Tested on:
	FreeBSD/32 6.3 (duty) in debug mode
	(h5committest not needed here, performed on trunk)