hdf5_ep

[svn-r4010] Purpose:
    Bug Fix
Description:
    uint64_t type was accidentally taken out and was causing tests on DEC
    UNIX to fail.
Solution:
    Brought back uint64_t type.
    Also cleaned up some comments and moved the sec2 specific macros back
    into the sec2 (and log) driver.
Platforms tested:
    DEC UNIX (gondolin)