Xnest: split off event handler

Tidy it up a bit and split the actual request handler from the request
reading loop, making upcoming reworks easier to review (smaller diffs).

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1661>

hw/xnest/Events.c

@@ -108,12 +108,9 @@ xnestQueueKeyEvent(int type, unsigned int keycode)
     QueueKeyboardEvents(xnestKeyboardDevice, type, keycode);
 }
 
-void
+static void
-xnestCollectEvents(void)
+xnest_handle_event(XEvent X)
 {
-    XEvent X;
-
-    while (XCheckIfEvent(xnestDisplay, &X, xnestNotExposurePredicate, NULL)) {
     switch (X.type) {
         case KeyPress:
         {
@@ -241,4 +238,13 @@ xnestCollectEvents(void)
             break;
     }
 }
+
+void
+xnestCollectEvents(void)
+{
+    XEvent X;
+
+    while (XCheckIfEvent(xnestDisplay, &X, xnestNotExposurePredicate, NULL)) {
+        xnest_handle_event(X);
+    }
 }