message: Add StdIndexedValue to EDSC helpers
  Add StdIndexedValue to EDSC helper so that we can use it
  to generated std.load and std.store in EDSC.
  Closes
  COPYBARA_INTEGRATE_REVIEW=https://github.com/tensorflow/mlir/pull/59 from dcaballe:dcaballe/std_indexed_value
diff: @@ -33,9 +33,12 @@ namespace edsc {
  template <typename Load, typename Store> class TemplatedIndexedValue;
  // By default, edsc::IndexedValue provides an index notation around the affine
  -// load and stores.
  +// load and stores. edsc::StdIndexedValue provides the standard load/store
  +// counterpart.
  using IndexedValue =
  TemplatedIndexedValue<intrinsics::affine_load, intrinsics::affine_store>;
  +using StdIndexedValue =
  + TemplatedIndexedValue<intrinsics::std_load, intrinsics::std_store>;
  // Base class for MemRefView and VectorView.
  class View {
  