euler inclusion
category: bugfix
bugzilla: 14007
CVE: NA

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In commit b8f8307ae1e9 ("pid_ns: Make pid_max per namespace"), pid_max
is made per namespace, so global pid_max in trace.h is unused now.
Remove it.
Signed-off-by: Nluojiajun <luojiajun3@huawei.com>
Reviewed-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>