generating function default settings from pg_proc.dat

Motivated by Bug 19409 [1] I decided to do something about a wart that
has bugged me for a while, namely the requirement to write stuff in
system_views.sql if you need to specify default values for function
arguments. Here's my attempt. The first patch here sets up the required
infrastructure. genbki.pl creates a file called function_defaults.sql
which is run by initdb at the appropriate time. There are two new fields
in pg_proc.dat entries: proargdflts,and provariadicdflt. These are
parsed and the appropriate CREATE OR REPLACE statement is generated and
placed in function_defaults.sql. The second patch applies this treatment
to 37 function definitions and removes the corresponding statements from
system_views.sql. This gets us closer to having pg_proc.dat as a single
source of truth.

cheers

andrew

[1]
https://www.postgresql.org/message-id/19409-e16cd2605e59a4af%40postgresql.org

--
Andrew Dunstan
EDB: https://www.enterprisedb.com