* genmodes.c (struct mode_data): Remove wider_2x member.
        (blank_mode): Adjust initializer.
        (calc_wider_mode): Use XALLOCAVEC.
        (emit_move_wider): Select double-width same-element vectors for
        2xwider vectors.
        * machmode.h (GET_MODE_2XWIDER_MODE): Update documentation.
        * config/i386/i386.c (doublesize_vector_mode): Remove.
        (expand_vselect_vconcat): Use GET_MODE_2XWIDER_MODE instead.

From-SVN: r182191