A display settings handler with a priority of 0 can not be properly registered due to how
X11DRV_Settings_SetHandler() is implemented. Fix a regression introduced by 9c99d9bc.

Spotted by Torge Matthies.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=50135Signed-off-by: Zhiyi Zhang <zzhang@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>