gtkglwidget: fix build error cause by api change in base-gl

commit 908c6c5d422ab069b5e642b06e536be2afea1816
Author: Haihua Hu <jared.hu@nxp.com>
Date:   Thu Apr 12 16:22:25 2018 +0800

    gloverlaycompositor: add subtitle rotate support follow video

    upstream status: Pending
    https://bugzilla.gnome.org/show_bug.cgi?id=790470

upsteam status: imx specific
1 file changed