Try setting JAVA_STARTED_ON_FIRST_THREAD_pid environment variable on macOS

The node-java project, which allows to embed Java and wrap its classes from inside a node.js app, has an analogous problem with AWT on macOS. The relevant issue is joeferner/node-java#21. But there is a [comment](https://github.com/joeferner/node-java/issues/21#issuecomment-373135774) saying you can set an environment variable `JAVA_STARTED_ON_FIRST_THREAD_pid=1` where `pid` is the process ID of the parent process, and then everything magically works. Let's try it!