Allow fallback from smithay to arboard when getting clipboard (#7976)

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Quick fix -- when the arboard and smithay features are both enabled,
Clipboard::get returns early if it can't find a smithay clipboard. This
PR just allows fallback to arboard instead of early-returning.

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/egui-winit/src/clipboard.rs

@@ -65,13 +65,12 @@ impl Clipboard {
             feature = "smithay-clipboard"
         ))]
         if let Some(clipboard) = &mut self.smithay {
-            return match clipboard.load() {
-                Ok(text) => Some(text),
+            match clipboard.load() {
+                Ok(text) => return Some(text),
                 Err(err) => {
                     log::error!("smithay paste error: {err}");
-                    None
                 }
-            };
+            }
         }
 
         #[cfg(all(