Fix a regression that wine-mono installer packages in the parent folder of build trees can not be
found since 405666b7.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=51209Signed-off-by: Zhiyi Zhang <zzhang@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>