Merge branch 'Bug fix and test case for special map value field '

Xu Kuohai says:

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This series is a follow-up to [0]. patch 1 updates sk_storage_map_test to
ensure special map value fields are not copied between user and kernel.
patch 0 fixes a bug found by the updated test.

[0] https://lore.kernel.org/bpf/1ca2e4e8-ed7e-9174-01f6-c14539b8b8b2@huawei.com/
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>