clang-format: update c/cc coding style

Update all cc code using .clang-format; please do so as well for future PRs
etc.; emacs has a handy 'clang-format' mode to make this automatic.

For comparing old changes with git blame, we can disregard this one using
--ignore-rev

(see https://www.moxio.com/blog/43/ignoring-bulk-change-commits-with-git-blame )

lib/utils/mu-readline.hh

@@ -26,15 +26,14 @@ namespace Mu {
  * @param histpath path to the history file
  * @param max_lines maximum number of history to save
  */
-void setup_readline(const std::string &histpath, size_t max_lines);
+void setup_readline(const std::string& histpath, size_t max_lines);
 
 /**
  * Shutdown readline
-*
+ *
  */
 void shutdown_readline();
 
-
 /**
  * Read a command line
  *
@@ -42,13 +41,13 @@ void shutdown_readline();
  *
  * @return the string read or empty
  */
-std::string read_line(bool &do_quit);
+std::string read_line(bool& do_quit);
 
 /**
  * Save a line to history (or do nothing when readline is not active)
  *
  * @param line a line.
  */
-void save_line(const std::string &line);
+void save_line(const std::string& line);
 
 } // namespace Mu