Bug#31177: Server variables can't be set to their current values

extra 5.1 fixes


mysql-test/t/order_fill_sortbuf-master.opt:
  If we set the variable below minimum, we'll get a warning
  at start-up that we don't want in the tests.

mysql-test/t/order_fill_sortbuf-master.opt

---set-variable=sort_buffer=0
+--set-variable=sort_buffer=32804