Use kernel.trace("sched:sched_process_fork") for kprocess.create when possible

Use kernel.trace("sched:sched_process_fork") for kprocess.create when possible

With optimization the copy_process function is often inlined making it
impossible for kprocess.create to probe the return of the copy_process
function.  The equivalent tracepoint sched:sched_process_fork should
be used instead to avoid that issue.  This change allows the
forktracker.stp and spawn_seekeer.stp examples to run even on kernels
where copy_process has been inlined.