hdf5_chunking_query_bmr

[svn-r16615] Purpose: Fix bug 1499

Description:
Due to a bug in H5F_super_read, every time a file with a user block was opened
it would grow by the size of the user block.  The bug has been fixed, and
comments have been added to clarify when an eoa address should be relative and
when it should be absolute.

Tested:
jam, linew (h5committest)