message: Enable Schwarz only with distributed.
diff: @@ -34,6 +34,12 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  #define GKO_PUBLIC_CORE_DISTRIBUTED_PRECONDITIONER_SCHWARZ_HPP_
  +#include <ginkgo/config.hpp>
  +
  +
  +#if GINKGO_BUILD_MPI
  +
  +
  #include <ginkgo/core/base/array.hpp>
  #include <ginkgo/core/base/lin_op.hpp>
  #include <ginkgo/core/distributed/matrix.hpp>
  @@ -177,4 +183,5 @@ private:
  } // namespace gko
  +#endif // GINKGO_BUILD_MPI
  #endif // GKO_PUBLIC_CORE_DISTRIBUTED_PRECONDITIONER_SCHWARZ_HPP_
  