suzerain: consolidate NRBC matrix access

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44039 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: loop up some explicit products

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44040 0bd85f0b-c151-43b9-a1e9-27231104551f