Fix WLR_DIRECTION enums.
Fix WLR_DIRECTION enums.

Having 0 as an enum value causes wlr_output_layout_adjacent_output() to
never match WLR_DIRECTION_UP.

swaywm/wlroots,swaywm/wlroots,SirCmpwn/wlroots,ascent12/wlroots,ascent12/wlroots