syscall: only get parent PID if SysProcAttr.Pdeathsig is set
The value of the parent PID is only used to check against get value
returned by getppid(2) in case SysProcAttr.Pdeathsig is non-zero. Avoid
the useless getpid(2) system call otherwise.
Cq-Include-Trybots: luci.golang.try:gotip-freebsd-amd64
Change-Id: If89f9c7acc82016ec359c79bd861d41460f42218
Reviewed-on: https://go-review.googlesource.com/c/go/+/699175
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Carlos Amedee <carlos@golang.org>