Add cmake_subdir_test

test/cmake_subdir_test/main.cpp

@@ -0,0 +1,8 @@
+#include <boost/mp11.hpp>
+using namespace boost::mp11;
+
+int main()
+{
+    using L1 = mp_list<int, float, int, float>;
+    return mp_size<mp_unique<L1>>::value == 2? 0: 1;
+}