iplink: implement support for selecting a master interface

Attaching an interface to a VRF is done by setting the interface's
master. Besides VRF, this can also be used for bridges.

function                                             old     new   delta
set_master                                             -     142    +142
do_iplink                                           1262    1357     +95
packed_usage                                       32546   32539      -7
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 237/-7)            Total: 230 bytes

Signed-off-by: Jan Luebbe <jluebbe@debian.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
3 files changed