function body (and other properties) as a function in the language
is created. This generalizes ad hoc code that already existed for
the built-in languages.
The validation now happens after the pg_proc tuple of the new function
is created, so it is possible to define recursive SQL functions.
Add some regression test cases that cover bogus function definition
attempts.
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.
