Merge branch 'selftests-Add-tests-for-mirroring-to-gretap'

Petr Machata says:

====================
selftests: Add tests for mirroring to gretap

This suite tests GRE-encapsulated mirroring. The general topology that
most of the tests use is as follows, but each test defines details of
the topology based on its needs, and some tests actually use a somewhat
different topology.

+---------------------+                      +---------------------+
| H1                  |                      |                  H2 |
|     + $h1           |                      |           $h2 +     |
+-----|---------------+                      +---------------|-----+
      |                                                      |
+-----|------------------------------------------------------|-----+
| SW  o---> mirror                                           |     |
| +---|------------------------------------------------------|---+ |
| |   + $swp1               BR                         $swp2 +   | |
| +--------------------------------------------------------------+ |
|                                                                  |
|     + $swp3          + gt6 (ip6gretap)    + gt4 (gretap)         |
+-----|----------------:--------------------:----------------------+
      |                :                    :
+-----|----------------:--------------------:----------------------+
|     + $h3            + h3-gt6(ip6gretap)  + h3-gt4 (gretap)      |
| H3                                                               |
+------------------------------------------------------------------+

The following axes of configuration space are tested:

- ingress and egress mirroring
- mirroring triggered by matchall and flower
- mirroring to ipgretap and ip6gretap
- remote tunnel reachable directly or through a next-hop route
- skip_sw as well as skip_hw configurations

Apart from basic tests with the above mentioned features, the following
tests are included:

- handling of changes to neighbors pertinent to routing decisions in
  mirrored underlay
- handling of configuration changes at the mirrored-to tunnel (endpoint
  addresses, upness)

A suite of mlxsw-specific tests will be part of a separate submission
through linux-mlxsw patch queue.
====================

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