server: Rename the wait_input_idle request to better reflect what it does.

Also get rid of the unused timeout field.
diff --git a/server/request.h b/server/request.h
index bbe1a7c..a6d720a 100644
--- a/server/request.h
+++ b/server/request.h
@@ -230,7 +230,7 @@
 DECL_HANDLER(get_msg_queue);
 DECL_HANDLER(set_queue_mask);
 DECL_HANDLER(get_queue_status);
-DECL_HANDLER(wait_input_idle);
+DECL_HANDLER(get_process_idle_event);
 DECL_HANDLER(send_message);
 DECL_HANDLER(post_quit_message);
 DECL_HANDLER(get_message);
@@ -449,7 +449,7 @@
     (req_handler)req_get_msg_queue,
     (req_handler)req_set_queue_mask,
     (req_handler)req_get_queue_status,
-    (req_handler)req_wait_input_idle,
+    (req_handler)req_get_process_idle_event,
     (req_handler)req_send_message,
     (req_handler)req_post_quit_message,
     (req_handler)req_get_message,