xcb: fix some memory leaks
xcb: fix some memory leaks

According to xcb docs, we are responsible for freeing this memory.

Signed-off-by: Rafaël Carré <29a40ef51885229607cd1e19e467be5d13190cad@videolan.org>
(cherry picked from commit 06005e87c76e739b1dd8a8003696571c184cf133)
Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1