after failed PyStd test, print hex code

Tests/Functional/PyStd/Check.cpp

@@ -54,7 +54,7 @@ std::unique_ptr<OutputData<double>> domainData(const std::string& test_name,
 #endif
     std::cout << "- system call: " << sys_command << std::endl;
     int err = std::system(sys_command.c_str());
-    std::cout << "- system call returned " << err << std::endl;
+    std::cout << "- system call returned " << err << " (0x" << std::hex << err << ")" << std::endl;
     if (err)
         throw std::runtime_error("Exported Python script did not execute properly");