Constant netlink_packet_route::rtnl::constants::RT_TABLE_COMPAT

pub const RT_TABLE_COMPAT: u8 = 252;

A route table introduced for compatibility with old software which do not support table IDs greater than 255. See commit 709772e6e065 in the kernel:

commit 709772e6e06564ed94ba740de70185ac3d792773
Author: Krzysztof Piotr Oledzki <ole@ans.pl>
Date:   Tue Jun 10 15:44:49 2008 -0700

    net: Fix routing tables with id > 255 for legacy software

    Most legacy software do not like tables > 255 as rtm_table is u8
    so tb_id is sent &0xff and it is possible to mismatch for example
    table 510 with table 254 (main).

    This patch introduces RT_TABLE_COMPAT=252 so the code uses it if
    tb_id > 255. It makes such old applications happy, new
    ones are still able to use RTA_TABLE to get a proper table id.

    Signed-off-by: Krzysztof Piotr Oledzki <ole@ans.pl>
    Acked-by: Patrick McHardy <kaber@trash.net>
    Signed-off-by: David S. Miller <davem@davemloft.net>