Codechange: Replace custom thread code with C++11 thread objects.

We assume a conforming C++11 compiler environment that has a valid <thread>-header.
Failure to run a real thread is handled gracefully.

src/os/windows/win32.h

@@ -39,12 +39,6 @@ HRESULT OTTDSHGetFolderPath(HWND, int, HANDLE, DWORD, LPTSTR);
 #define SHGFP_TYPE_CURRENT 0
 #endif /* __MINGW32__ */
 
-#ifdef _MSC_VER
-void SetWin32ThreadName(DWORD dwThreadID, const char* threadName);
-#else
-static inline void SetWin32ThreadName(DWORD dwThreadID, const char* threadName) {}
-#endif
-
 void Win32SetCurrentLocaleName(const char *iso_code);
 int OTTDStringCompare(const char *s1, const char *s2);