selftests: tls: test splicing cmsgs

mainline inclusion
from mainline-v5.16-rc3
commit d87d67fd
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56S5K?from=project-issue

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d87d67fd61ef4e7619eb24ab20cba3250a6444e8



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Make sure we correctly reject splicing non-data records.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>