fdo#73199 librelogo: path, interop. and color name fixes

Change-Id: I201c498b0ff002ed92c2fcf9847ac1efc50b3fde
Reviewed-on: https://gerrit.libreoffice.org/7244
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>