Wayland: Remove superfluous initialize to NULL

The whole window struct has already been cleared to zero.

(cherry picked from commit 216ea3d735)

src/wl_window.c

@@ -944,8 +944,6 @@ int _glfwPlatformCreateWindow(_GLFWwindow* window,
         }
     }
 
-    window->wl.currentCursor = NULL;
-
     window->wl.monitors = calloc(1, sizeof(_GLFWmonitor*));
     window->wl.monitorsCount = 0;
     window->wl.monitorsSize = 1;