hdf5_ep

[svn-r6692] Purpose:
feature.

Description:
Added the option of "setenv3" which sets the environment variable
that has three components like env AR="ar -X 64".  It is another
kludge like setenv2.  Got to code in a better 'setenv' option.

Platforms tested:
Copper (because its -64 compiling needs that AR set as above).
Eirene (where it usually launches).
Did not do h5committest which does not test bin/runtest.

Misc. update: