Merge branch 'selftests-net-bridge-add-tests-for-mldv2'

Nikolay Aleksandrov says:

====================
selftests: net: bridge: add tests for MLDv2

This is the second selftests patch-set for the new multicast functionality
which adds tests for the bridge's MLDv2 support. The tests use full
precooked packets which are sent via mausezahn and the resulting state
after each test is checked for proper X,Y sets, (*,G) source list, source
list entry timers, (S,G) existence and flags, packet forwarding and
blocking, exclude group expiration and (*,G) auto-add. The first 3 patches
factor out common functions which are used by IGMPv3 tests in lib.sh and
add support for IPv6 test UDP packet, then patch 4 adds the first test with
the initial MLDv2 setup.
The following new tests are added:
 - base case: MLDv2 report ff02::cc is_include
 - include -> allow report
 - include -> is_include report
 - include -> is_exclude report
 - include -> to_exclude report
 - exclude -> allow report
 - exclude -> is_include report
 - exclude -> is_exclude report
 - exclude -> to_exclude report
 - include -> block report
 - exclude -> block report
 - exclude timeout (move to include + entry deletion)
 - S,G port entry automatic add to a *,G,exclude port

The variable names and set notation are the same as per RFC 3810,
for more information check RFC 3810 sections 2.3 and 7.
====================

Link: https://lore.kernel.org/r/20201103172412.1044840-1-razor@blackwall.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>