Revert "events: use input_state_e in input_state_changed."

This reverts commit 627aaa88.

Well, we do need to define the type first. Limitation of how we declared events.

include/vlc_events.h

@@ -140,7 +140,7 @@ typedef struct vlc_event_t
         /* Input (thread) events */
         struct vlc_input_state_changed
         {
-            input_state_e new_state;
+            int new_state;
         } input_state_changed;
 
         /* Input item events */