x11-wm/river: unbreak on aarch64 after 1f734d3bbcda

zig-cache/zig-wayland/common.zig:103:21: error: cast increases pointer alignment

@ptrCast(*const fn (*Obj, Payload, Data) void, implementation)(
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

zig-cache/zig-wayland/common.zig:103:68: note: '?*const anyopaque' has alignment '1'

@ptrCast(*const fn (*Obj, Payload, Data) void, implementation)(
                                               ^~~~~~~~~~~~~~

zig-cache/zig-wayland/common.zig:103:30: note: '*const fn(*river_layout_v3_server.LayoutV3, river_layout_v3_server.LayoutV3.Request, ?*anyopaque) void' has alignment '4'

@ptrCast(*const fn (*Obj, Payload, Data) void, implementation)(
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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