wayland: only bind to input method when enabled

Having multiple input methods at once causes behaviour defined by the
Wayland compositor. In a recent update by Phoc, the most recently
started input method would take priority to demonstrate the instability.

Since the keyboard driver for Wayland can handle a emitting input
without an input method, only try to bind to an input method when it is
enabled.

src/wayland/dispatcher.rs

@@ -68,14 +68,18 @@ impl Dispatcher {
             Err(_) => None,
         };
 
-        let im_man = match globals.bind(&queue, 1..=1, ()) {
+        let im_man = if cfg.wayland_im_enable() {
-            Ok(g) => Some(g),
-            Err(_) => None,
-        };
-
             let _: Result<zwp_input_method_v1::ZwpInputMethodV1, BindError>
                   = globals.bind(&queue, 1..=1, ());
 
+            match globals.bind(&queue, 1..=1, ()) {
+                Ok(g) => Some(g),
+                Err(_) => None,
+            }
+        } else {
+            None
+        };
+
         let frac_scale_man = match globals.bind(&queue, 1..=1, ()) {
             Ok(g) => Some(g),
             Err(_) => None,