xfce4-whiskermenu-plugin: Disable support for positioning in Wayland

MarIuX does not ship *gtk-layer-shell-0*, checked for by default:

    -- Checking for module 'gtk-layer-shell-0>=0.7'
    --   No package 'gtk-layer-shell-0' found
    CMake Error at /usr/share/cmake-3.25/Modules/FindPkgConfig.cmake:607 (message):
      A required package was not found
    Call Stack (most recent call first):
      /usr/share/cmake-3.25/Modules/FindPkgConfig.cmake:829 (_pkg_check_modules_internal)
      panel-plugin/CMakeLists.txt:80 (pkg_check_modules)

Description:

> -DENABLE_GTK_LAYER_SHELL=[ON]
>     Use GtkLayerShell to position menu in Wayland.

xfce4-whiskermenu-plugin.be0

@@ -24,7 +24,8 @@ SRCURL[0]="https://beehive.molgen.mpg.de/fe60c0c93f72d1533f6fc972d3a80c99/xfce4-
 
 mee_configure() {
     bee_configure \
-        -DENABLE_ACCOUNTS_SERVICE=OFF
+        -DENABLE_ACCOUNTS_SERVICE=OFF \
+        -DENABLE_GTK_LAYER_SHELL=OFF
 }
 
 #mee_build() {