tydedef extraction - back to the future

Many years ago we in effect moved maintenance of the typedefs list for
pgindent into the buildfarm client. The reason was that there were a
number of typedefs that were platform dependent, so we wanted to have
coverage across a number of platforms to get a comprehensive list.

Lately, this has caused some dissatisfaction, with people wanting the
logic for this moved back into core code, among other reasons so we're
not reliant on one person - me - for changes. I share this
dissatisfaction. Indeed, IIRC the use of the buildfarm was originally
intended as something of a stopgap. Still, we do need to multi-platform
support.

Attached is an attempt to thread this needle. The core is a new perl
module that imports the current buildfarm client logic. The intention is
that once we have this, the buildfarm client will switch to using the
module (if found) rather than its own built-in logic. There is precedent
for this sort of arrangement (AdjustUpgrade.pm). Accompanying the new
module is a standalone perl script that uses the new module, and
replaces the current shell script (thus making it more portable).

One thing this is intended to provide for is getting typedefs for
non-core code such as third party extensions, which isn't entirely
difficult
(<https://adpgtech.blogspot.com/2015/05/running-pgindent-on-non-core-code-or.html>)
but it's not as easy as it should be either.

Comments welcome.

cheers

andrew

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