Merge branch 'move-sockopt-tests'

Merge branch 'move-sockopt-tests'

Stanislav Fomichev says:

====================
Now that test_progs is shaping into more generic test framework,
let's convert sockopt tests to it. This requires adding
a helper to create and join a cgroup first (test__join_cgroup).
Since we already hijack stdout/stderr that shouldn't be
a problem (cgroup helpers log to stderr).

The rest of the patches just move sockopt tests files under prog_tests/
and do the required small adjustments.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>