Fix windows SEH hook when crashing in an std::thread

Follows 107d3d461f and other 'pthread->std::thread' diffs.

Windows uses Structured Exception Handling to allow reporting errors
(both C++ and hardware) nicely. This works by wrapping the code in a
__try __catch block.
The pthread wrapper did this automatically, but we now need to do it
explicitly for std::thread.

Tested by: Stan
Differential Revision: https://code.wildfiregames.com/D3261
This was SVN commit r24530.

source/test_setup.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2020 Wildfire Games.
+/* Copyright (C) 2021 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -77,7 +77,7 @@ class MiscSetup : public CxxTest::GlobalFixture
 		setlocale(LC_CTYPE, "UTF-8");
 #endif
 
-		ThreadUtil::SetMainThread();
+		Threading::SetMainThread();
 
 		g_Profiler2.Initialise();
 		m_ScriptEngine = new ScriptEngine;