updates for handling optional argument in system functions

Hi everyone,

I noticed how it was preferred to define optional arguments with the
system functions in system_functions.sql instead of defining them in
pg_proc.dat.

I took a gross stab at updating the ones that ended in _ext, which
turned out to be 7 declarations across 6 system functions, and created a
patch per system function, hoping it would be easier to review.

Perhaps the most interesting thing to share is the total reduction of
the lines of code, although system_functions.sql only grows:

src/backend/catalog/system_functions.sql | 49 ++++++++
src/backend/utils/adt/ruleutils.c | 130 ----------------------
src/include/catalog/pg_proc.dat | 36 ++----
3 files changed, 56 insertions(+), 159 deletions(-)

Is that something we want?

Regards,
Mark
--
Mark Wong <markwkm(at)gmail(dot)com>
EDB https://enterprisedb.com