pg_lsn cast to/from int8

Is there a reason we don't have casts between int8 and pg_lsn? AFAICT it
works fine if I create the cast manually... Is it because of
signed/unsigned if people have really really many transactions?

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/