The wsrep_cluster_weight status variable is not supported

Current version of Galera does not support the wsrep_cluster_weight
status variable, which causes the galera_pc_weight test (from the
galera_3nodes suite) to fail:

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galera_3nodes.galera_pc_weight 'innodb' [ fail ]
Test ended at 2019-02-08 12:27:07

CURRENT_TEST: galera_3nodes.galera_pc_weight
— /home/panda/mariadb_work/mysql-test/suite/galera_3nodes/r/galera_pc_weight.result 2019-02-06 15:27:27.000000000 +0100
+++ /home/panda/mariadb_work/mysql-test/suite/galera_3nodes/r/galera_pc_weight.reject 2019-02-08 12:27:06.771991509 +0100
@@ -1,11 +1,9 @@
connection node_1;
SELECT VARIABLE_VALUE = 3 FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_weight';
VARIABLE_VALUE = 3
-1
SET GLOBAL wsrep_provider_options = 'pc.weight=3';
SELECT VARIABLE_VALUE = 5 FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_weight';
VARIABLE_VALUE = 5
-1
SET GLOBAL wsrep_provider_options = 'gmcast.isolate=1';
connection node_2;
SET SESSION wsrep_sync_wait=0;
@@ -16,7 +14,6 @@
wsrep_cluster_size 2
SHOW STATUS LIKE 'wsrep_cluster_weight';
Variable_name Value
-wsrep_cluster_weight 0
...
mysqltest: Result length mismatch
...
***Warnings generated in error logs during shutdown after running tests: galera_3nodes.galera_pc_weight

2019-02-08 12:27:05 0 [Warning] WSREP: 67b51ae4overriding reported weight for 67b3e5c3
2019-02-08 12:27:05 0 [Warning] WSREP: 67b5158foverriding reported weight for 67b3e5c3
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