selftests/bpf: check that modifier resolves after pointer

stable inclusion
from stable-v5.10.177
commit 8c42442887db59ac4b67aeaf8825d1192bc783d6
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I88YNP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c42442887db59ac4b67aeaf8825d1192bc783d6



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[ Upstream commit dfdd608c ]

Add a regression test that ensures that a VAR pointing at a
modifier which follows a PTR (or STRUCT or ARRAY) is resolved
correctly by the datasec validator.

Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230306112138.155352-3-lmb@isovalent.com


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>
(cherry picked from commit 1728dd91)