fdo#82259 Hardcode script for "GB18030 Bitmap"

Change-Id: I3b3ad955f1793197e970c837ff53aa85a74b8cfb
Reviewed-on: https://gerrit.libreoffice.org/11213
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>