Wayland: Fix behavior of leaving full screen mode

These changes make GLFW fullscreen more consistent, but unfortunately
also make GLFW even more oblivious to user-initiated XDG shell
fullscreen changes.

Fixes #1995

(cherry picked from commit ddd087d662)

src/wl_platform.h

@@ -181,6 +181,7 @@ typedef struct _GLFWwindowWayland
     int                         width, height;
     GLFWbool                    visible;
     GLFWbool                    maximized;
+    GLFWbool                    activated;
     GLFWbool                    hovered;
     GLFWbool                    transparent;
     struct wl_surface*          surface;
@@ -212,8 +213,6 @@ typedef struct _GLFWwindowWayland
 
     struct zwp_idle_inhibitor_v1*          idleInhibitor;
 
-    GLFWbool                    wasFullscreen;
-
     struct {
         GLFWbool                           serverSide;
         struct wl_buffer*                  buffer;