selftests/seccomp: Update kernel config

selftests/seccomp: Update kernel config

[ Upstream commit 2c07343abd8932200a45ff7b10950e71081e9e77 ]

seccomp_bpf.c uses unshare(CLONE_NEWPID), which requires CONFIG_PID_NS
to be set.

Cc: Kees Cook <keescook@chromium.org>
Cc: Shuah Khan <shuah@kernel.org>
Fixes: 6a21cc50f0c7 ("seccomp: add a return code to trap to userspace")
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Acked-by: Tycho Andersen <tycho@tycho.pizza>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201202162643.249276-1-mic@digikod.net
Signed-off-by: Sasha Levin <sashal@kernel.org>