Add some cpp<->chai performance tests

performance_tests/profile_cpp_calls_2.cpp

@@ -0,0 +1,20 @@
+#include <chaiscript/chaiscript.hpp>
+#include <chaiscript/chaiscript_stdlib.hpp>
+
+double f(const std::string &, double, bool) noexcept {
+  return .0;
+}
+
+int main()
+{
+  chaiscript::ChaiScript chai(chaiscript::Std_Lib::library());
+
+  chai.add(chaiscript::fun(&f), "f");
+
+  chai.eval(R"(
+      for (var i = 0; i < 100000; ++i) {
+        f("str", 1.2, false);
+      }
+    )");
+
+}