MDEV-37784 Introduce @@new_mode: support all values being hidden

Fix my_print_help() to print "No currently supported values".
It used to print the first value even if it was hidden.

Author: spetrunia

mysql-test/main/mysqld--help.result

@@ -784,8 +784,7 @@ The following specify which files/extra groups are read (specified before remain
  Number of seconds to wait for a block to be written to a
  connection before aborting the write
  --new-mode=name     Used to introduce new behavior to existing MariaDB
- versions. Any combination of: FIX_DISK_TMPTABLE_COSTS, or
- ALL to set all combinations
+ versions. No currently supported values.
  --note-verbosity=name 
  Verbosity level for note-warnings given to the user. See
  also @@sql_notes. Any combination of: basic, 

mysys/my_getopt.c

@@ -1647,6 +1647,8 @@ void my_print_help(const struct my_option *options)
     if (optp->comment && *optp->comment)
     {
       uint count;
+      uint hidden_value_count= 0;
+      my_bool skip_or_all_message= 0;
 
       if (col > name_space)
       {
@@ -1667,8 +1669,22 @@ void my_print_help(const struct my_option *options)
         count= optp->typelib->count;
         break;
       case GET_SET: 
-        typelib_help= ". Any combination of: ";
+        if (optp->typelib->hidden_values)
+        {
+          /* Count how many values are hidden */
+          for (const int *val= optp->typelib->hidden_values; *val>= 0; val++)
+            hidden_value_count++;
+        }
         count= optp->typelib->count;
+        if (count == hidden_value_count)
+        {
+          /* All values are hidden */
+          typelib_help= ". No currently supported values.";
+          count= 0;
+          skip_or_all_message= 1;
+        }
+        else
+          typelib_help= ". Any combination of: ";
         break;
       case GET_FLAGSET:
         typelib_help= ". Takes a comma-separated list of option=value pairs, "
@@ -1680,9 +1696,9 @@ void my_print_help(const struct my_option *options)
           strstr(optp->comment, optp->typelib->type_names[0]) == NULL)
       {
         uint i;
+        my_bool printing_first= 1;
         col= print_comment(typelib_help, col, name_space, comment_space);
-        col= print_comment(optp->typelib->type_names[0], col, name_space, comment_space);
-        for (i= 1; i < count; i++)
+        for (i= 0; i < count; i++)
         {
           my_bool skip_value= 0;
           /* Do not print the value if it is listed in hidden_values */
@@ -1700,11 +1716,14 @@ void my_print_help(const struct my_option *options)
           }
           if (skip_value)
             continue;
-          col= print_comment(", ", col, name_space, comment_space);
+          if (printing_first)
+            printing_first= 0;
+          else
+            col= print_comment(", ", col, name_space, comment_space);
           col= print_comment(optp->typelib->type_names[i], col, name_space, comment_space);
         }
       }
-      if ((optp->var_type & GET_TYPE_MASK) == GET_SET)
+      if ((optp->var_type & GET_TYPE_MASK) == GET_SET && !skip_or_all_message)
         col= print_comment(", or ALL to set all combinations", col, name_space, comment_space);
       if (optp->deprecation_substitute != NULL)
       {