Use write result for pid done signal
Use write result for pid done signal

Prevent warnings during build for a signal write to indicate that the
pid file has been created. This is a warning under -Wunused-result on
linux.

Closes #12562.

PiperOrigin-RevId: 346091438

safarmer/bazel,perezd/bazel,twitter-forks/bazel,katre/bazel,twitter-forks/bazel,bazelbuild/bazel,safarmer/bazel,meteorcloudy/bazel,twitter-forks/bazel,bazelbuild/bazel,katre/bazel,ButterflyNetwork/bazel,katre/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,safarmer/bazel,perezd/bazel,meteorcloudy/bazel,cushon/bazel,perezd/bazel,safarmer/bazel,cushon/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,bazelbuild/bazel,twitter-forks/bazel,katre/bazel,safarmer/bazel,perezd/bazel,meteorcloudy/bazel,cushon/bazel,katre/bazel,meteorcloudy/bazel,safarmer/bazel,cushon/bazel,bazelbuild/bazel,bazelbuild/bazel,twitter-forks/bazel,twitter-forks/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,perezd/bazel,twitter-forks/bazel,perezd/bazel,cushon/bazel,cushon/bazel,perezd/bazel,katre/bazel