x11/libxfce4menu: Update fix for leaked keygrabs when layout changes

[madpilot]

Summary

Update to the fix proposed by cem in [1].

This patch uses the glib GArray API to have growing list of old keycodes instead of using a fixed size array.

The patch is submitted upstream at [2].

[1] https://reviews.freebsd.org/D24338

[2] https://gitlab.xfce.org/xfce/libxfce4ui/-/merge_requests/1

Test Plan

I'm runing this on my machine without problems.

I'd like someone else to confirm it works properly.

[madpilot]

x11/libxfce4menu/files/patch-libxfce4kbd-private_xfce-shortcuts-grabber.c

17–18

I suspect this check is not really necessary anymore, but not completely sure.

I also was not able to find documentation about the behavior of g_array_index() when one asks to access an element beyond the end of the array.

[madpilot]

Align patch with the one sent upstream.