suzerain: #3055 #3056 stub extrema API

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suzerain: decouple headers w/ forward decls

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suzerain: #3055 #3056 quick implementation

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44179 0bd85f0b-c151-43b9-a1e9-27231104551f