sshd: sync tracing disable with upstream

Old versions of FreeBSD do not support using id 0 to refer to the
current pid for procctl, so pass getpid() explicitly.

Although this is not required in current FreeBSD branches I am merging
it to reduce differences with upstream.

Obtained from: OpenSSH commit 0f7e1eba5525

(cherry picked from commit 4232f36eda60406642fc6cfef605b6d38fc0a7c0)
(cherry picked from commit 733bf3b108f8b69295778bab5f7d680b9a8e6dba)