MDEV-30473 : Do not allow GET_LOCK() / RELEASE_LOCK() in cluster

If WSREP_ON=ON do not allow GET_LOCK and RELEASE_LOCK functions.
Instead print clear error message.

mysql-test/suite/galera/r/galera_locks_funcs.result

+connection node_2;
+connection node_1;
+CREATE TABLE t (c DOUBLE,c2 INT,PRIMARY KEY(c)) ENGINE=InnoDB;
+INSERT INTO t values (1,1);
+SELECT GET_LOCK('a',1);
+ERROR 42000: This version of MariaDB doesn't yet support 'GET_LOCK in cluster (WSREP_ON=ON)'
+SHOW WARNINGS;
+Level	Code	Message
+Error	1235	This version of MariaDB doesn't yet support 'GET_LOCK in cluster (WSREP_ON=ON)'
+SELECT * FROM t;
+c	c2
+1	1
+SELECT RELEASE_LOCK('a');
+ERROR 42000: This version of MariaDB doesn't yet support 'RELEASE_LOCK in cluster (WSREP_ON=ON)'
+SHOW WARNINGS;
+Level	Code	Message
+Error	1235	This version of MariaDB doesn't yet support 'RELEASE_LOCK in cluster (WSREP_ON=ON)'
+COMMIT;
+DROP TABLE t;

mysql-test/suite/galera/t/galera_locks_funcs.test

+--source include/galera_cluster.inc
+
+CREATE TABLE t (c DOUBLE,c2 INT,PRIMARY KEY(c)) ENGINE=InnoDB;
+INSERT INTO t values (1,1);
+--error ER_NOT_SUPPORTED_YET
+SELECT GET_LOCK('a',1);
+SHOW WARNINGS;
+SELECT * FROM t;
+--error ER_NOT_SUPPORTED_YET
+SELECT RELEASE_LOCK('a');
+SHOW WARNINGS;
+COMMIT;
+DROP TABLE t;
+

sql/item_create.cc

@@ -4933,6 +4933,13 @@ Create_func_get_lock Create_func_get_lock::s_singleton;
 Item*
 Create_func_get_lock::create_2_arg(THD *thd, Item *arg1, Item *arg2)
 {
+#ifdef WITH_WSREP
+  if (WSREP_ON && WSREP(thd))
+  {
+    my_error(ER_NOT_SUPPORTED_YET, MYF(0), "GET_LOCK in cluster (WSREP_ON=ON)");
+    return NULL;
+  }
+#endif /* WITH_WSREP */
   thd->lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION);
   thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT);
   return new (thd->mem_root) Item_func_get_lock(thd, arg1, arg2);
@@ -6535,6 +6542,13 @@ Create_func_release_lock Create_func_release_lock::s_singleton;
 Item*
 Create_func_release_lock::create_1_arg(THD *thd, Item *arg1)
 {
+#ifdef WITH_WSREP
+  if (WSREP_ON && WSREP(thd))
+  {
+    my_error(ER_NOT_SUPPORTED_YET, MYF(0), "RELEASE_LOCK in cluster (WSREP_ON=ON)");
+    return NULL;
+  }
+#endif /* WITH_WSREP */
   thd->lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION);
   thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT);
   return new (thd->mem_root) Item_func_release_lock(thd, arg1);