fdo#75056: Overline attribute needs special treatment as well.

Also fix the export of underline types as well.  It was always saved
as a single line.

(cherry picked from commit fcf5b5c081ded93b12dd888236d0a860b7693ed1)

Change-Id: I88cb0f3702a6afc14544ecbce8f200b5422fd78f
Signed-off-by: Fridrich Strba <fridrich@documentfoundation.org>