Add some more windows checks, remove outdated CI tests

(Xenial is no longer supported).

test/test_windows_defs_2.cpp

@@ -0,0 +1,29 @@
+/*
+*
+* Copyright (c) 2021
+* John Maddock
+*
+* Use, modification and distribution are subject to the
+* Boost Software License, Version 1.0. (See accompanying file
+* LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+*
+*/
+
+#if defined(_WIN32) && !defined(BOOST_REGEX_NO_W32)
+//
+// Make sure our forward declarations match those in windows.h:
+//
+
+#define NO_STRICT
+
+#include <boost/regex.hpp>
+#include <windows.h>
+
+void test_proc()
+{
+   std::string text, re;
+   boost::regex exp(re);
+   regex_match(text, exp);
+}
+
+#endif