don't mirror 0, RECT_EMPTY, 0, RECT_EMPTY rectangle
don't mirror 0, RECT_EMPTY, 0, RECT_EMPTY rectangle

leave it untouched to make gtk3 rtl spin buttons possible
where the additional mirrorValue contains the region
of the spinbuttons to render within this rectangle

Change-Id: I2648d98ed36373c95947cc4d78e2e54797f01155
Reviewed-on: https://gerrit.libreoffice.org/17940
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