for rtl we mirror the position of popdowns, so we need
to know their initial desired position before they have actually
appeared yet and have a valid maGeometry.nX, so fill in the
hoped-for position as the current position

Change-Id: Ic22dc3e5d9922f5d48bbbdaad53caabff57188d8
Reviewed-on: https://gerrit.libreoffice.org/43459Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>