Commit 08bf6e52 seems not to have
used the correct *GetDatum and PG_GETARG_* macros for the SQL types
in some cases, and some of the SQL types seem to have been poorly
chosen, too.  Try to fix it.  I'm not sure if this is the reason
why the buildfarm is currently unhappy with this code, but it
seems like a good place to start.

Buildfarm unhappiness reported by Tom Lane.