Two bug fixes.

1. Add schur_templates.cc to Android.mk
2. When detecting the Schur structure of the Jacobian,
   the check for whether linear solver being used is indeed
   of Schur type or not, should use the LinearSolver::Options
   struct created and populated by the preprocessor rather than
   depending on the value in the input Solver::Options. The reason
   is that the preprocessor may change the linear solver type
   depending on the lack of a Schur structure in the problem.

Change-Id: I6f018f6817c05d704409181c7b1e25155528ab84