hdf5_ep

[svn-r1594] 
added a conditional for __INT64 in the part of the code where the file
addresses are given types.  so now if the sizeof__int64 is >=8 then haddr_t
is typedefed to an unsigned __int64 and the HADDR_UNDEF = ((haddr_t)(__int64)(-1)).
I used the unsigned long long as my example.