libgltf: rename pathces dir to patches

Change-Id: Ibd28dcdab17b1248d62205e5bf94d0c92c3f8841
Reviewed-on: https://gerrit.libreoffice.org/10750
Reviewed-by: Zolnai Tamás <tamas.zolnai@collabora.com>
Tested-by: Zolnai Tamás <tamas.zolnai@collabora.com>