child_process.spawnSync returns status=0 when signal=SIGKILL

[brandones]

• Version: v6.9.5
• Platform: Linux 1a7889358561 4.8.6-x86_64-linode78 deps: update openssl to 1.0.1j #1 SMP Tue Nov 1 14:51:21 EDT 2016 x86_64 Linux
• Subsystem: child_process

When the process forked by child_process.spawnSync is send SIGKILL, the returned object has status == 0 while signal == SIGKILL. This differs from the behavior of child_process.spawn, for which the Exit event handler is called with status == null and signal == SIGKILL, per the documentation.

Reproduction at https://github.com/brandones/nodejs-child-process-bug-repro

[cjihrig]

Proposed fix in #11288.