MDEV-22535 fixup: Define a single-caller function inline

Let us avoid any overhead in release builds, for an empty function.

sql/table.cc

@@ -9922,7 +9922,7 @@ bool TABLE::export_structure(THD *thd, Row_definition_list *defs)
   return false;
 }
 
-/*
+/**
   @brief
     Initialize all the opt_range structures that are used to stored the
     estimates when the range optimizer is run.
@@ -9931,7 +9931,7 @@ bool TABLE::export_structure(THD *thd, Row_definition_list *defs)
     to be able to find wrong usage of data with valgrind or MSAN.
 */
 
-void TABLE::initialize_opt_range_structures()
+inline void TABLE::initialize_opt_range_structures()
 {
   TRASH_ALLOC((void*)&opt_range_keys, sizeof(opt_range_keys));
   TRASH_ALLOC(opt_range, s->keys * sizeof(*opt_range));

sql/table.h

@@ -1637,7 +1637,8 @@ struct TABLE
   bool is_filled_at_execution();
 
   bool update_const_key_parts(COND *conds);
-  void initialize_opt_range_structures();
+
+  inline void initialize_opt_range_structures();
 
   my_ptrdiff_t default_values_offset() const
   { return (my_ptrdiff_t) (s->default_values - record[0]); }