hdf5_ep

[svn-r9830] Purpose:
Bug fix

Description:
Fortran and C++ API failed to compile because they need to use
H5E_LEN which was removed.

Solution:
Restored the H5E_LEN definition.
A permenant solution is still needed.

Platforms tested:
H5committested. (heping, sol, and copper all compiled fine again but
sol had an error in testerror.sh which seemed to be a different
problem.
Also tested in tg-NSCA.