Merge branch 'selftests-bpf-convert-test_tc_tunnel-sh-to-test_progs'

Alexis Lothoré says:

====================
Hello,
this is the v3 of test_tc_tunnel conversion into test_progs framework.
This new revision:
- fixes a few issues spotted by the bot reviewer
- removes any test ensuring connection failure (and so depending on a
  timout) to keep the execution time reasonable

test_tc_tunnel.sh tests a variety of tunnels based on BPF: packets are
encapsulated by a BPF program on the client egress. We then check that
those packets can be decapsulated on server ingress side, either thanks
to kernel-based or BPF-based decapsulation. Those tests are run thanks
to two veths in two dedicated namespaces.

- patches 1 and 2 are preparatory patches
- patch 3 introduce tc_tunnel test into test_progs
- patch 4 gets rid of the test_tc_tunnel.sh script

The new test has been executed both in some x86 local qemu machine, as
well as in CI:

  # ./test_progs -a tc_tunnel
  #454/1   tc_tunnel/ipip_none:OK
  #454/2   tc_tunnel/ipip6_none:OK
  #454/3   tc_tunnel/ip6tnl_none:OK
  #454/4   tc_tunnel/sit_none:OK
  #454/5   tc_tunnel/vxlan_eth:OK
  #454/6   tc_tunnel/ip6vxlan_eth:OK
  #454/7   tc_tunnel/gre_none:OK
  #454/8   tc_tunnel/gre_eth:OK
  #454/9   tc_tunnel/gre_mpls:OK
  #454/10  tc_tunnel/ip6gre_none:OK
  #454/11  tc_tunnel/ip6gre_eth:OK
  #454/12  tc_tunnel/ip6gre_mpls:OK
  #454/13  tc_tunnel/udp_none:OK
  #454/14  tc_tunnel/udp_eth:OK
  #454/15  tc_tunnel/udp_mpls:OK
  #454/16  tc_tunnel/ip6udp_none:OK
  #454/17  tc_tunnel/ip6udp_eth:OK
  #454/18  tc_tunnel/ip6udp_mpls:OK
  #454     tc_tunnel:OK
  Summary: 1/18 PASSED, 0 SKIPPED, 0 FAILED
====================

Link: https://patch.msgid.link/20251027-tc_tunnel-v3-0-505c12019f9d@bootlin.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>