Core: Reserve memory map as early as possible

Protects against all the other stuff we load eating up all the address space that we want

pcsx2-gsrunner/Main.cpp

@@ -899,6 +899,8 @@ int main(int argc, char* argv[])
 	if (!GSRunner::ParseCommandLineArgs(argc, argv, params))
 		return EXIT_FAILURE;
 
+	SysMemory::ReserveMemory();
+
 	if (s_use_window.value_or(true) && !GSRunner::CreatePlatformWindow())
 	{
 		Console.Error("Failed to create window.");