with OPAQUE, as per recent pghackers discussion. I still want to do some
more work on the 'cstring' pseudo-type, but I'm going to commit the bulk
of the changes now before the tree starts shifting under me ...
in pghackers list. Support for oldstyle internal functions is gone
(no longer needed, since conversion is complete) and pg_language entry
'internal' now implies newstyle call convention. pg_language entry
'newC' is gone; both old and newstyle dynamically loaded C functions
are now called language 'C'. A newstyle function must be identified
by an associated info routine. See src/backend/utils/fmgr/README.