Post-fix for MDEV-11688 fil_crypt_threads_end() tries to create threads

fil_crypt_threads_cleanup(): Do nothing if nothing was initialized.

storage/innobase/fil/fil0crypt.cc

@@ -2397,6 +2397,9 @@ void
 fil_crypt_threads_cleanup()
 /*=======================*/
 {
+	if (!fil_crypt_threads_inited) {
+		return;
+	}
 	os_event_destroy(fil_crypt_event);
 	os_event_destroy(fil_crypt_threads_event);
 	mutex_free(&fil_crypt_threads_mutex);

storage/xtradb/fil/fil0crypt.cc

@@ -2465,8 +2465,9 @@ void
 fil_crypt_threads_end()
 /*===================*/
 {
-	/* stop threads */
-	fil_crypt_set_thread_cnt(0);
+	if (fil_crypt_threads_inited) {
+		fil_crypt_set_thread_cnt(0);
+	}
 }
 
 /*********************************************************************
@@ -2476,6 +2477,9 @@ void
 fil_crypt_threads_cleanup()
 /*=======================*/
 {
+	if (!fil_crypt_threads_inited) {
+		return;
+	}
 	os_event_free(fil_crypt_event);
 	os_event_free(fil_crypt_threads_event);
 	mutex_free(&fil_crypt_threads_mutex);