bugfix(x11): crash when querying xsettings prop fails

Don't crash when xsettings query fails with _present_ xsettings.

Closes: https://github.com/rust-windowing/winit/issues/3573

src/platform_impl/linux/x11/util/randr.rs

@@ -53,6 +53,7 @@ impl XConnection {
             .get_string("Xft.dpi", "")
             .and_then(|s| f64::from_str(s).ok())
     }
+
     pub fn get_output_info(
         &self,
         resources: &monitor::ScreenResources,