Refactor unsymmetric_linear_solver_test

1. Break up unsymmetric_linear_solver_test into
   a. dense_linear_solver_test which covers DENSE_QR and
      DENSE_NORMAL_CHOLESKY.
   b. sparse_normal_cholesky_solver_test which covers
      SPARSE_NORMAL_CHOLESKY.

2. dense_linear_solver_test has been completely re-written. It now
   uses value parameterized tests for better logging. The number of
   test problems as been increased to 2. Last but not the least
   the actual test of correctness is not based on a golden solution
   computed using another linear solver. We now compute the residual
   and ensure that it is small.

https://github.com/ceres-solver/ceres-solver/issues/279

Change-Id: I9546a43e8ae85c31b2096a99405e47da326755ee

internal/ceres/CMakeLists.txt

@@ -299,6 +299,7 @@ if (BUILD_TESTING AND GFLAGS)
   ceres_test(covariance)
   ceres_test(cubic_interpolation)
   ceres_test(detect_structure)
+  ceres_test(dense_linear_solver)
   ceres_test(dense_sparse_matrix)
   ceres_test(dynamic_autodiff_cost_function)
   ceres_test(dynamic_compressed_row_sparse_matrix)
@@ -343,6 +344,7 @@ if (BUILD_TESTING AND GFLAGS)
   ceres_test(small_blas)
   ceres_test(solver)
   ceres_test(sparse_cholesky)
+  ceres_test(sparse_normal_cholesky_solver)
 
   # TODO(sameeragarwal): This test should ultimately be made
   # independent of SuiteSparse.
@@ -356,7 +358,6 @@ if (BUILD_TESTING AND GFLAGS)
   ceres_test(triplet_sparse_matrix)
   ceres_test(trust_region_minimizer)
   ceres_test(trust_region_preprocessor)
-  ceres_test(unsymmetric_linear_solver)
   ceres_test(visibility)
   ceres_test(visibility_based_preconditioner)