hdf5_msb

[svn-r21354] Issue 7674 - CLANG compiler complained about the line (about 800):
	tempint = (tempint >> packed_data_offset) & packed_data_mask;
The right shift may cause undefined behavior if PACKED_DATA_OFFSET is 
32-bit or more. For every kind of native integers, I changed the code 
to make it zero if PACKED_DATA_OFFSET is greater than or equal to the
size of integer.

Tested on Mac OS Lion with CLANG compiler and jam, koala, and linew.