bpf: test_sysctl run failed on Debian9

[Ma Xinjian <max.xinjian@xxxxxxxxx>]

Hi,  Andrey.

I noticed you add test_sysctl to tools/bpf, so drop this problem to you.

When I run selftests: bpf: test_sysctl, failed with 
"(test_sysctl.c:1490: errno: Permission denied) >>> Loading program 
(./test_sysctl_prog.o) error."


Testing env: "Debian GNU/Linux 9 (stretch)"

kernel: 5.7.0-rc2    5.7.0-rc1  5.6  both failed


Whole run log and kconfig please see the attatchment.

Error info

```

root@vm-snb-42 
/usr/src/perf_selftests-x86_64-rhel-7.6-kselftests-ae83d0b416db002fe95601e7f97f64b59514d936/tools/testing/selftests/bpf# 
./test_sysctl

Test case: sysctl wrong attach_type .. [PASS]
Test case: sysctl:read allow all .. [PASS]
Test case: sysctl:read deny all .. [PASS]

[snip]

libbpf: -- END LOG --
libbpf: failed to load program 'cgroup/sysctl'
libbpf: failed to load object './test_sysctl_prog.o'
(test_sysctl.c:1490: errno: Permission denied) >>> Loading program 
(./test_sysctl_prog.o) error.

Test case: C prog: read tcp_mem .. [FAIL]
Summary: 37 PASSED, 3 FAILED

```

--
Best Regards.
Ma Xinjian

Attachment: bpf_test_sysctl_log.gz
Description: application/gzip

Attachment: kconfig.gz
Description: application/gzip