`get_stdopt` caters only to the c++ kernel

[anutosh491]

xeus-cpp/src/xinterpreter.cpp

Lines 76 to 101 in c7628c6

	static std::string get_stdopt()
	{
	// We need to find what's the C++ version the interpreter runs with.
	const char* code = R"(
	int __get_cxx_version () {
	#if __cplusplus > 202302L
	return 26;
	#elif __cplusplus > 202002L
	return 23;
	#elif __cplusplus > 201703L
	return 20;
	#elif __cplusplus > 201402L
	return 17;
	#elif __cplusplus > 201103L || (defined(_WIN32) && _MSC_VER >= 1900)
	return 14;
	#elif __cplusplus >= 201103L
	return 11;
	#else
	return 0;
	#endif
	}
	__get_cxx_version ()
	)";
	auto cxx_version = Cpp::Evaluate(code);
	return std::to_string(cxx_version);
	}

Defines version for the kernel based on __get_cxx_version and this variable ends up taking 0 for the kernel version (for any C kernel). For example from the wasm kernel (pasting the wasm content)

  (func $__get_cxx_version (;2;) (export "__get_cxx_version") (result i32)
    i32.const 0
  )

So a kernel info request would show the version to be 0 instead of C23.

We should probably fetch information from the Kernel spec whether a C or C++ kernel is defined and use get_stdopt accordingly !