3DS: Set stack size w/o starting SVM inside a thread

This commit introduces a simpler method for setting the stack size. By setting a global variable __stacksize__,
we can override the identically-named, weak-attributed __stacksize__ defined in libctru. This is an intentional
feature of libctru, and renders it unnecessary to run ScummVM from within a thread.

Source: devkitPro/libctru@192b88b
Explanation: https://gbatemp.net/threads/homebrew-development.360646/page-245#post-6362424
Usage in the wild: https://github.com/masterfeizz/ioQuake3DS/blob/master/code/ctr/ctr_main.c#L44

backends/platform/3ds/main.cpp

@@ -30,28 +30,8 @@ enum {
 	SYSTEM_MODEL_2DS = 3
 };
 
-struct CommandLine {
-	int argumentCount;
-	char** argumentsValue;
-
-	CommandLine(int argc, char** argv): argumentCount(argc), argumentsValue(argv) {}
-};
-
-static void mainThreadFunc(void *threadParams) {
-	g_system = new N3DS::OSystem_3DS();
-	assert(g_system);
-
-#ifdef DYNAMIC_MODULES
-	PluginManager::instance().addPluginProvider(new CTRPluginProvider());
-#endif
-
-	CommandLine *commandLine = static_cast<CommandLine *>(threadParams);
-	int res = scummvm_main(commandLine->argumentCount, commandLine->argumentsValue);
-
-	g_system->destroy();
-
-	threadExit(res);
-};
+// Set the size of the stack.
+u32 __stacksize__ = 64 * 1024;
 
 int main(int argc, char *argv[]) {
 	// Initialize basic libctru stuff
@@ -75,17 +55,16 @@ int main(int argc, char *argv[]) {
 	socInit((u32 *)soc_sharedmem, soc_sharedmem_size);
 #endif
 
-	// Start ScummVM in a separate thread to be able to set the stack size.
-	// The default stack is not large enough.
-	CommandLine commandLine(argc, argv);
+	g_system = new N3DS::OSystem_3DS();
+	assert(g_system);
+
+#ifdef DYNAMIC_MODULES
+	PluginManager::instance().addPluginProvider(new CTRPluginProvider());
+#endif
 
-	s32 mainThreadPriority = 0;
-	svcGetThreadPriority(&mainThreadPriority, CUR_THREAD_HANDLE);
+	int res = scummvm_main(argc, argv);
 
-	Thread mainThread = threadCreate(&mainThreadFunc, &commandLine, 64 * 1024, mainThreadPriority, -2, false);
-	threadJoin(mainThread, U64_MAX);
-	int res = threadGetExitCode(mainThread);
-	threadFree(mainThread);
+	g_system->destroy();
 
 	// Turn on both screen backlights before exiting.
 	if (R_SUCCEEDED(gspLcdInit())) {