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

This reverts commit 844ddb11.

This fixes MDEV-30967, MDEV-31325, MDEV-31388

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

@@ -4933,13 +4933,6 @@ 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);
@@ -6542,13 +6535,6 @@ 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);