hdf5_ep

[svn-r2009] Purpose
    Bug fix.
Description
    When converting a floating point zero to a different format (e.g. Cray),
    the mantissa part was not set to zeros complete.  Cray does not
    seem to mind since the exponent part was set to all 0's.  Somehow,
    the HDF4 does not like it and convert that pattern to a non-zero
    value in IEEE.
Solution
    corrected the code to set the whole mantissa to zeros completely.
Platform tested:
    J90 & Solaris 2.7.