hdf5_msb

[svn-r16849] Description:
	Bring r16848 from revise_chunks branch to trunk:

	Add test (and bugfixes) for detecting if a filter makes a chunk size
larger than can be encoded in a 32-bit variable (in the file).

Tested on:
       FreeBSD/32 6.3 (duty) in debug mode
	(h5committest not needed, multi-platform testing done on branch)