client almost builds

vendor/cryptopp/TestPrograms/test_cxx11_lambda.cpp

@@ -0,0 +1,10 @@
+// https://en.cppreference.com/w/cpp/feature_test
+int main(int argc, char* argv[])
+{
+#if __cpp_lambdas >= 200907L
+    int x[1];
+#else
+    int x[-1];
+#endif
+    return 0;
+}