Initialize graphics in OutputDevice::getFallbackFont.
Initialize graphics in OutputDevice::getFallbackFont.

OutputDevice::getFallbackFont requires mpGraphics to be created/initialized.
Without the check and initialization OutputDevice::getFallbackFont will segfault.

Change-Id: I18225a24a6767933c8f1ff8f1cfd392543a95132
Reviewed-on: https://gerrit.libreoffice.org/14287
Reviewed-by: Caolán McNamara <301f5784f9f6aac04077f24f1e5abc31af69d401@redhat.com>
Tested-by: Caolán McNamara <301f5784f9f6aac04077f24f1e5abc31af69d401@redhat.com>

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core