Wayland: Fix events emitted before ack_configure

Window iconfication and maximization events were being emitted before
xdg_surface::configure, making it possible for user code to indirectly
commit surface changes from those event callbacks before
xdg_surface::ack_configure.

This postpones those events until after the ack has been sent.

(cherry picked from commit 85f5a51912)

src/wl_platform.h

@@ -189,6 +189,10 @@ typedef struct _GLFWwindowWayland
 
     struct {
         int                     width, height;
+        GLFWbool                maximized;
+        GLFWbool                iconified;
+        GLFWbool                activated;
+        GLFWbool                fullscreen;
     } pending;
 
     struct {