apprt/gtk: fix build errors

Author: mitchellh

src/apprt/gtk/class/application.zig

@@ -1111,7 +1111,7 @@ pub const Application = extern struct {
         self.syncActionAccelerator("win.split-down", .{ .new_split = .down });
         self.syncActionAccelerator("win.split-left", .{ .new_split = .left });
         self.syncActionAccelerator("win.split-up", .{ .new_split = .up });
-        self.syncActionAccelerator("win.copy", .{ .copy_to_clipboard = {} });
+        self.syncActionAccelerator("win.copy", .{ .copy_to_clipboard = .mixed });
         self.syncActionAccelerator("win.paste", .{ .paste_from_clipboard = {} });
         self.syncActionAccelerator("win.reset", .{ .reset = {} });
         self.syncActionAccelerator("win.clear", .{ .clear_screen = {} });

src/apprt/gtk/class/window.zig

@@ -1801,7 +1801,7 @@ pub const Window = extern struct {
         _: ?*glib.Variant,
         self: *Window,
     ) callconv(.c) void {
-        self.performBindingAction(.copy_to_clipboard);
+        self.performBindingAction(.{ .copy_to_clipboard = .mixed });
     }
 
     fn actionPaste(