Bug#30050452: CRASH WHEN EXECUTING "SELECT SLEEP(10)" THROUGH CURSOR (WITH THREAD-POOL)

Post-push fix for broken build:
 struct 'Key_value_store_logger' was previously declared as a class;
 this is valid, but may result in linker errors under the Microsoft C++ ABI [-Werror,-Wmismatched-tags]

Change-Id: Iee44de91ef55c4375c680e15f44d560d03ec54ad
(cherry picked from commit 6575dd86299a21b1de8e4452c058b91fd9e4b415)

Author: Tor Didriksen

storage/temptable/include/temptable/kv_store.h

@@ -59,8 +59,8 @@ class Key_value_store
     : public Key_value_store_logger<Key_value_store<Lock, KeyValueImpl>,
                                     DEBUG_BUILD> {
   /** Do not break encapsulation when using CRTP. */
-  friend struct Key_value_store_logger<Key_value_store<Lock, KeyValueImpl>,
-                                       DEBUG_BUILD>;
+  friend class Key_value_store_logger<Key_value_store<Lock, KeyValueImpl>,
+                                      DEBUG_BUILD>;
 
   /** Help ADL to bring debugging/logging symbols into the scope. */
   using Key_value_store_logger<Key_value_store<Lock, KeyValueImpl>,