Add X11 opt-in function for device events

Previously on X11, by default all global events were broadcasted to
every winit application. This unnecessarily drains battery due to
excessive CPU usage when moving the mouse.

To resolve this, device events are now ignored by default and users must
manually opt into it using
`EventLoopWindowTarget::set_filter_device_events`.

Fixes (#1634) on Linux.

src/platform_impl/linux/mod.rs

@@ -30,7 +30,9 @@ use crate::{
     dpi::{PhysicalPosition, PhysicalSize, Position, Size},
     error::{ExternalError, NotSupportedError, OsError as RootOsError},
     event::Event,
-    event_loop::{ControlFlow, EventLoopClosed, EventLoopWindowTarget as RootELW},
+    event_loop::{
+        ControlFlow, DeviceEventFilter, EventLoopClosed, EventLoopWindowTarget as RootELW,
+    },
     icon::Icon,
     monitor::{MonitorHandle as RootMonitorHandle, VideoMode as RootVideoMode},
     window::{CursorIcon, Fullscreen, UserAttentionType, WindowAttributes},
@@ -732,7 +734,7 @@ impl<T: 'static> EventLoop<T> {
     }
 
     pub fn window_target(&self) -> &crate::event_loop::EventLoopWindowTarget<T> {
-        x11_or_wayland!(match self; EventLoop(evl) => evl.window_target())
+        x11_or_wayland!(match self; EventLoop(evlp) => evlp.window_target())
     }
 }
 
@@ -793,6 +795,16 @@ impl<T> EventLoopWindowTarget<T> {
             }
         }
     }
+
+    #[inline]
+    pub fn set_device_event_filter(&mut self, _filter: DeviceEventFilter) {
+        match *self {
+            #[cfg(feature = "wayland")]
+            EventLoopWindowTarget::Wayland(_) => (),
+            #[cfg(feature = "x11")]
+            EventLoopWindowTarget::X(ref mut evlp) => evlp.set_device_event_filter(_filter),
+        }
+    }
 }
 
 fn sticky_exit_callback<T, F>(