Merge branch 'Multipath-tests-for-tunnel-devices'

Petr Machata says:

====================
Multipath tests for tunnel devices

This patchset adds a test for ECMP and weighted ECMP between two GRE
tunnels.

In patches #1 and #2, the function multipath_eval() is first moved from
router_multipath.sh to lib.sh for ease of reuse, and then fixed up.

In patch #3, the function tc_rule_stats_get() is parameterized to be
useful for egress rules as well.

In patch #4, a new function __simple_if_init() is extracted from
simple_if_init(). This covers the logic that needs to be done for the
usual interface: VRF migration, upping and installation of IP addresses.

Patch #5 then adds the test itself.

Additionally in patch #6, a requirement to add diagrams to selftests is
documented.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>