Fix Bug #53947 InnoDB: Assertion failure in thread 4224 in file .\sync\sync0sync.c line 324

Destroy the rw-lock object before freeing the memory it is occupying.
If we do not do this, then the mutex that is contained in the rw-lock
object btr_search_latch_temp->mutex gets "freed" and subsequently
mutex_free() from sync_close() hits a mutex whose memory has been
freed and crashes.

Approved by:	Heikki (via IRC)
Discussed with:	Calvin

storage/innobase/btr/btr0sea.c

@@ -194,6 +194,7 @@ void
 btr_search_sys_free(void)
 /*=====================*/
 {
+	rw_lock_free(&btr_search_latch);
 	mem_free(btr_search_latch_temp);
 	btr_search_latch_temp = NULL;
 	mem_heap_free(btr_search_sys->hash_index->heap);