Add support of EIGEN_SPARSE type in IsSparseLinearAlgebraLibraryTypeAvailable function.

Change-Id: I53f1a245509a216f31e1824486a13c4bac548a7f

internal/ceres/types.cc

diff --git a/internal/ceres/types.cc b/internal/ceres/types.cc
index cf70408..275d7f8 100644
--- a/internal/ceres/types.cc
+++ b/internal/ceres/types.cc
@@ -342,6 +342,14 @@
 #endif
   }
 
+  if (type == EIGEN_SPARSE) {
+#ifdef CERES_USE_EIGEN_SPARSE
+    return true;
+#else
+    return false;
+#endif
+  }
+
   LOG(WARNING) << "Unknown sparse linear algebra library " << type;
   return false;
 }