* machmode.def (V1DImode): New mode.  A single element vector.
* tree.h (TI_UV1DI_TYPE, TI_V1DI_TYPE): New tree_index enums.
  (unsigned_V1DI_type_node, V1D1_type_node): New type nodes.
* tree.c (build_common_tree_nodes_2): Build
  unsigned_V1DI_type_node and V1D1_type_node.
* c-common.c (c_common_type_for_mode): Return
  unsigned_V1DI_type_node or V1D1_type_node for V1DImode.
* rtl.c (class_narrowest_): Start integer vector nodes with V1DImode.

From-SVN: r57248