Add prompt for non-libedit read-from-std loop.

wcclparser/main.cpp

@@ -26,6 +26,7 @@ namespace {
 void std_read_loop(boost::function<bool (const std::string&)>& line_cb)
 {
 	while (std::cin.good()) {
+		std::cout << _prompt << std::flush;
 		std::string s;
 		getline(std::cin, s);
 		if (line_cb(s)) {