hdf5_ep

[svn-r8677] Purpose:
    Code cleanup & optimization

Description:
    Remove old structures that used a union to store information about the
dataspace extent and just store the information directly in the dataspace
extent itself.

    Remove ifdef'd references to permutation ordering in dataspaces.  We'll
definitely need more than this code if/when we implement this feature.

    Change allocation of dataspace information from calloc() to malloc().

Platforms tested:
    Solaris 2.7 (arabica)
    FreeBSD 4.10 (sleipnir) w/parallel
    Too minor to require h5committest