procctl(PROC_REAP_KILL): align error reporting with pgkill(2)

[kib]

Summary

ESRCH from cr_cansignal() means that the target process should be not
visible to the initiator.  So do not report pids with ESRCH result.

Noted by:       markj

[olce]

sys/kern/kern_procctl.c

270–274

Looks wrong. If ESRCH is returned, this code will still proceed to pksignal(), whereas the purpose of cr_cansignal() returning ESRCH is exactly to avoid the target being signaled.

[kib]

Return on any error, not excluding ESRCH.

[markj]

Thank you. It looks right, I would add a short comment like /* Hide ESRCH errors to ensure that this function cannot be used as an oracle for process visibility. */

[kib]

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