Make OpenGL 2D rendering working again.

Change-Id: I29101aee77ac37f5a8e1b929793d7554bc425b26
Reviewed-on: https://gerrit.libreoffice.org/10075
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Kohei Yoshida <libreoffice@kohei.us>