xwayland: set seat

This makes e.g. the clipboard work.

 river/InputManager.zig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/river/InputManager.zig b/river/InputManager.zig
index 80fd9e8..1175b5d 100644
--- a/river/InputManager.zig
+++ b/river/InputManager.zig
@@ -17,6 +17,7 @@
 
 const Self = @This();
 
+const build_options = @import("build_options");
 const std = @import("std");
 
 const c = @import("c.zig");
@@ -55,6 +56,8 @@ pub fn init(self: *Self, server: *Server) !void {
     self.default_seat = &seat_node.data;
     self.seats.prepend(seat_node);
 
+    if (build_options.xwayland) c.wlr_xwayland_set_seat(server.wlr_xwayland, self.default_seat.wlr_seat);
+
     self.exclusive_client = null;
 
     // Set up all listeners