... use the same size as VLC does.

See:
https://opengrok.libreoffice.org/xref/core/avmedia/source/vlc/vlcplayer.cxx#167

Change-Id: Ib878ded6c8aacf3a04227ab9efaa59b388f8ff51
Reviewed-on: https://gerrit.libreoffice.org/43827Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit a2ec3024)
Reviewed-on: https://gerrit.libreoffice.org/45781Reviewed-by: Xisco Faulí <xiscofauli@libreoffice.org>