I modified FindSilo so that it can work with silo with and without hdf5
support. It looks for sio configured with hdf5 support first, then without
it. I also modified build_visit to create the config-site file properly in
the 2 situations. This resolves #561.



git-svn-id: http://visit.ilight.com/svn/visit/trunk/src@13962 18c085ea-50e0-402c-830e-de6fd14e8384