MDEV-33157 WSREP: Fix function pointer mismatch

wsrep_plugin_init(), wsrep_plugin_deinit(): Remove these dummy functions
in order to fix an error that would be flagged by cmake -DWITH_UBSAN=ON
when using clang.

wsrep_show_ready(), wsrep_show_bf_aborts(): Correct the signature.

sql/wsrep_mysqld.cc

@@ -512,7 +512,8 @@ my_bool wsrep_ready_get (void)
   return ret;
 }
 
-int wsrep_show_ready(THD *thd, SHOW_VAR *var, char *buff)
+int wsrep_show_ready(THD *thd, SHOW_VAR *var, void *buff,
+                     system_status_var *, enum_var_type)
 {
   var->type= SHOW_MY_BOOL;
   var->value= buff;

sql/wsrep_mysqld.h

@@ -148,7 +148,8 @@ extern char*       wsrep_cluster_capabilities;
 
 int  wsrep_show_status(THD *thd, SHOW_VAR *var, void *buff,
                        system_status_var *status_var, enum_var_type scope);
-int  wsrep_show_ready(THD *thd, SHOW_VAR *var, char *buff);
+int  wsrep_show_ready(THD *thd, SHOW_VAR *var, void *buff,
+                      system_status_var *, enum_var_type);
 void wsrep_free_status(THD *thd);
 void wsrep_update_cluster_state_uuid(const char* str);
 

sql/wsrep_plugin.cc

@@ -18,18 +18,6 @@
 
 #include <mysql/plugin.h>
 
-static int wsrep_plugin_init(void *p)
-{
-  WSREP_DEBUG("wsrep_plugin_init()");
-  return 0;
-}
-
-static int wsrep_plugin_deinit(void *p)
-{
-  WSREP_DEBUG("wsrep_plugin_deinit()");
-  return 0;
-}
-
 struct Mysql_replication wsrep_plugin= {
   MYSQL_REPLICATION_INTERFACE_VERSION
 };
@@ -42,8 +30,8 @@ maria_declare_plugin(wsrep)
   "Codership Oy",
   "Wsrep replication plugin",
   PLUGIN_LICENSE_GPL,
-  wsrep_plugin_init,
-  wsrep_plugin_deinit,
+  NULL,
+  NULL,
   0x0100,
   NULL, /* Status variables */
   NULL, /* System variables */

sql/wsrep_thd.cc

@@ -36,7 +36,7 @@ static Wsrep_thd_queue* wsrep_rollback_queue= 0;
 static Atomic_counter<uint64_t> wsrep_bf_aborts_counter;
 
 
-int wsrep_show_bf_aborts (THD *thd, SHOW_VAR *var, char *buff,
+int wsrep_show_bf_aborts (THD *thd, SHOW_VAR *var, void *, system_status_var *,
                           enum enum_var_type scope)
 {
   wsrep_local_bf_aborts= wsrep_bf_aborts_counter;

sql/wsrep_thd.h

@@ -82,7 +82,7 @@ class Wsrep_thd_queue
   mysql_cond_t     COND_wsrep_thd_queue;
 };
 
-int wsrep_show_bf_aborts (THD *thd, SHOW_VAR *var, char *buff,
+int wsrep_show_bf_aborts (THD *thd, SHOW_VAR *var, void *, system_status_var *,
                           enum enum_var_type scope);
 bool wsrep_create_appliers(long threads, bool mutex_protected=false);
 void wsrep_create_rollbacker();