MDEV-4786 - merge 10.0-monty - 10.0

Fixed connect.grant failure.

sql/create_options.cc:
  Keep "first" list intact, allocate new list for merge result.
  
  Normally "first" is options list on TABLE_SHARE. ALTER TABLE may fail
  after the merge and leave share with corrupt list in the table definition
  cache.
sql/create_options.h:
  Construct engine_option_value from another engine_option_value.

sql/create_options.cc

@@ -743,9 +743,9 @@ engine_option_value *merge_engine_table_options(engine_option_value *first,
   DBUG_ENTER("merge_engine_table_options");
   LINT_INIT(end);
 
-  /* find last element */
-  if (first && second)
-    for (end= first; end->next; end= end->next) /* no-op */;
+  /* Create copy of first list */
+  for (opt= first, first= 0; opt; opt= opt->next)
+    new (root) engine_option_value(opt, &first, &end);
 
   for (opt= second; opt; opt= opt->next)
     new (root) engine_option_value(opt->name, opt->value, opt->quoted_value,

sql/create_options.h

@@ -34,6 +34,13 @@ class engine_option_value: public Sql_alloc
   bool parsed;                  ///< to detect unrecognized options
   bool quoted_value;            ///< option=VAL vs. option='VAL'
 
+  engine_option_value(engine_option_value *src,
+                      engine_option_value **start, engine_option_value **end) :
+    name(src->name), value(src->value),
+    next(NULL), parsed(src->parsed), quoted_value(src->quoted_value)
+  {
+    link(start, end);
+  }
   engine_option_value(LEX_STRING &name_arg, LEX_STRING &value_arg, bool quoted,
                       engine_option_value **start, engine_option_value **end) :
     name(name_arg), value(value_arg),