Currently, I am using int32 simply because int64 is causing some issues. The issue is that genbki.pl is not able to associate it with the int8 type as defined in pg_type.h. Therefore Schema_pg_authid in schemapg.h isn't defined correctly. I've been digging and scratching my head on this one but I have reached a point where I think it would be better just to ask.
Attached is a quite trivial patch that addresses the int64 (C) to int8 (SQL) mapping issue.
Further digging revealed that Catalog.pm wasn't accounting for int64 (thanks Stephen). Would it be better to include this change as a separate patch (as attached) or would it be preferable to include with a larger role attribute bitmask patch?