* config/arc/arc.c (DTPOFF_ZERO_SYM): Define.
        (arc_legitimize_tls_address): Don't change local-dynamic to
        local-exec if that'd loose 9-bit offset addressing.
        Where we have a base address, emit it as the second element in
        the UNSPEC_TLS_OFF vector.
        Force base into register.
        (arc_output_pic_addr_const) <UNSPEC_TLS_OFF>: If a base is given,
        output it too.