mu-server: add a bit more debugging info

lib/utils/mu-readline.cc

@@ -64,6 +64,13 @@ static bool        is_a_tty{};
 static std::string hist_path;
 static size_t      max_lines{};
 
+bool
+Mu::have_readline()
+{
+	return HAVE_READLINE != 0;
+}
+
+
 void
 Mu::setup_readline(const std::string& histpath, size_t maxlines)
 {

lib/utils/mu-readline.hh

@@ -50,4 +50,12 @@ std::string read_line(bool& do_quit);
  */
 void save_line(const std::string& line);
 
+
+/**
+ * Do we have the non-shim readline?
+ *
+ * @return true or failse
+ */
+bool have_readline();
+
 } // namespace Mu