DumpSchema command line option segfaults on Linux

[Stan]

When running the following command on Linux (macOS and Windows seem unaffected):

$ pyrogenesis -mod=public -dumpSchema

The file is generated correctly but a segfault occurs.

TIMER| InitVfs: 11.0418 ms
FILES| Main log written to '/home/builder/.config/0ad/logs/mainlog.html'
FILES| Interesting log written to '/home/builder/.config/0ad/logs/interestinglog.html'
TIMER| CONFIG_Init: 61.519 ms
Generated entity.rng
mozilla::detail::MutexImp::~MutexImpl: pthread_mutex_destroy failed: Device or resource busy
Segmentation fault (core dumped)

​GameSetup.cpp#L600

Line
593	if (args.Has("dumpSchema"))
594	{
595	CSimulation2 sim(NULL, g_ScriptContext, NULL);
596	sim.LoadDefaultScripts();
597	std::ofstream f("entity.rng", std::ios_base::out | std::ios_base::trunc);
598	f << sim.GenerateSchema();
599	std::cout << "Generated entity.rng\n";
600	exit(0);
601	}

It seems that replacing exit(0) by return false prevents the segfault

 if (args.Has("dumpSchema"))
 {
     CSimulation2 sim(NULL, g_ScriptContext, NULL);
     sim.LoadDefaultScripts();
     std::ofstream f("entity.rng", std::ios_base::out | std::ios_base::trunc);
     f << sim.GenerateSchema();
     std::cout << "Generated entity.rng\n";
-    exit(0);
+    return false;
 }

[Itms]

I think changing exit(0) to return false is absolutely correct.

Init returning false is going to cause Shutdown to be called with the SHUTDOWN_FROM_CONFIG flag, which reduces the shutdown sequence to everything inited before the config system. In Init, we see that the config was the last thing to be inited before the schema was generated. The simulation created in the block will be properly freed first when returning.

exit(0) is in the code since the introduction of the dumpSchema feature (r7452) and it is anterior to the refinements of the init/shutdown code, so that explains why return false was not used. But return false is, with the current code, the correct way to end the dumpSchema sequence.

[Itms]

In 27470:

Follow proper Shutdown sequence when using -dumpSchema, fixes #6696.

Also fix an incorrect code comment, and prevent Atlas from being started with -dumpSchema.

Reviewed By: phosit
Differential Revision: ​https://code.wildfiregames.com/D4903