hdf5_ep

[svn-r9234] Purpose:
    Code cleanup

Description:
    Tweak recent "forward compatibility" changes to the H5E* API (which allowed
for the old H5E API functions to remain unchanged) by allowing for the error
stack callback function (H5E_auto_t) to also remain unchanged from the 1.6
branch.  This required changing the H5E{get|set}_auto routines to have the
old style H5E_auto_t type (which didn't have a stack ID parameter) and the new
H5E{get|set}_auto_stack routines to have a newer "H5E_auto_stack_t" type (which
has a stack ID parameter).  This should make the H5E API changes as forwardly
compatible as possible.
    One side-affect of this change was that it was impossible to determine if
the current auto error callback was the old style (H5E_auto_t) or the new style
(H5E_auto_stack_t) of callback, so a new API function (H5Eauto_is_stack) was
adde to query this.

Platforms tested:
    FreeBSD 4.10 (sleipnir)
    IRIX64 6.5 (modi4)
    h5committest