Bug #44179 reset slave crashes in my_error when reset_logs returns non-zero

my_error() was invoked in reset_slave()'s with purge_relay_logs()-failing branch
without passing sql_errno to it.

Fixed with setting sql_errno= ER_RELAY_LOG_FAIL in the purge_relay_logs()-failing branch.

sql/sql_repl.cc

@@ -1026,7 +1026,10 @@ int reset_slave(THD *thd, Master_info* mi)
   if ((error= purge_relay_logs(&mi->rli, thd,
 			       1 /* just reset */,
 			       &errmsg)))
+  {
+    sql_errno= ER_RELAY_LOG_FAIL;
     goto err;
+  }
 
   /*
     Clear master's log coordinates and reset host/user/etc to the values