MDEV-18496 Crash when Aria encryption is enabled but plugin not available

wait_while_table_is_used() should return an error if handler::extra() fails

mysql-test/suite/maria/encrypt-no-key.result

+call mtr.add_suppression('Unknown key id 1. Can''t continue');
+set global aria_encrypt_tables= 1;
+create table t1 (pk int primary key, a int, key(a)) engine=aria transactional=1;
+alter table t1 disable keys;
+insert into t1 values  (1,1);
+alter table t1 enable keys;
+ERROR HY000: Unknown key id 1. Can't continue!
+drop table t1;
+set global aria_encrypt_tables= default;

mysql-test/suite/maria/encrypt-no-key.test

+#
+# MDEV-18496 Crash when Aria encryption is enabled but plugin not available
+#
+call mtr.add_suppression('Unknown key id 1. Can''t continue');
+
+set global aria_encrypt_tables= 1;
+create table t1 (pk int primary key, a int, key(a)) engine=aria transactional=1;
+alter table t1 disable keys;
+insert into t1 values  (1,1);
+error 192;
+alter table t1 enable keys;
+drop table t1;
+set global aria_encrypt_tables= default;

sql/sql_base.cc

@@ -1892,7 +1892,7 @@ bool wait_while_table_is_used(THD *thd, TABLE *table,
                    FALSE);
   /* extra() call must come only after all instances above are closed */
   if (function != HA_EXTRA_NOT_USED)
-    (void) table->file->extra(function);
+    DBUG_RETURN(table->file->extra(function));
   DBUG_RETURN(FALSE);
 }
 

storage/myisammrg/myrg_extra.c

@@ -31,7 +31,7 @@ int myrg_extra(MYRG_INFO *info,enum ha_extra_function function,
   DBUG_PRINT("info",("function: %lu", (ulong) function));
 
   if (!info->children_attached)
-    DBUG_RETURN(1);
+    DBUG_RETURN(0);
   if (function == HA_EXTRA_CACHE)
   {
     info->cache_in_use=1;