Add CMake tests

test/quick.cpp

@@ -0,0 +1,15 @@
+
+// Copyright 2019 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+// http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+
+using namespace boost::variant2;
+
+int main()
+{
+    variant<float, int> v( 2 );
+    return get<1>( v ) == 2? 0: 1;
+}