Add check for dynamic sparsity in Solver::Options::IsValid.

Dynamic sparsity should only be used with SPARSE_NORMAL_CHOLESKY.

Change-Id: I8dd33c05ec0337b3c13b547ecffe3aefc3e5ab12

internal/ceres/solver.cc

diff --git a/internal/ceres/solver.cc b/internal/ceres/solver.cc
index 8f19886..e99ddc9 100644
--- a/internal/ceres/solver.cc
+++ b/internal/ceres/solver.cc
@@ -216,6 +216,12 @@
     return false;
   }
 
+  if (options.dynamic_sparsity &&
+      options.linear_solver_type != SPARSE_NORMAL_CHOLESKY) {
+    *error = "Dynamic sparsity is only supported with SPARSE_NORMAL_CHOLESKY.";
+    return false;
+  }
+
   return true;
 }