make history widget respect history_control settings (bug #39728) * input.cc(octave_gets): append entry to the history widget only if really something has been added to the history * oct-hist.cc(edit_history_add_hist,octave_history_write_timestamp): append entry to the history widget only if really something has benn added to the history * cmd-hist.cc(class gnu_history): do_add with boolean return value, (do_add): return true if something has been added to the history via ::octave_add_history, false otherwise, (command_history::add): now returns the return value of do_add, (command_history::do_add): return false * cmd-hist.h: add and do_add now with boolean return value

--- a/liboctave/util/cmd-hist.h
+++ b/liboctave/util/cmd-hist.h
@@ -61,7 +61,7 @@
 
   static bool ignoring_entries (void);
 
-  static void add (const std::string&);
+  static bool add (const std::string&);
 
   static void remove (int);
 
@@ -156,7 +156,7 @@
 
   virtual bool do_ignoring_entries (void) const;
 
-  virtual void do_add (const std::string&);
+  virtual bool do_add (const std::string&);
 
   virtual void do_remove (int);