Merge branch 'BPF selftests misc fixes'

Geliang Tang says:

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v2:
 - only check the first "link" (link_nl) in test_mixed_links().
 - Drop patch 2 in v1.

This patchset fixes a segfault and a bpf object leak in test_progs.

It is a resend patch 1 out of "skip ENOTSUPP BPF selftests" set as Eduard
suggested. Together with another fix for xdp_adjust_tail.
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>