Subject: make postgresql find its plugins

From: Gábor Boskovits <[email-masked]>
Date: Mon, 24 Sep 2018 13:23:38 +0200

It works fine for me.

Some things I noticed while checking this:
1. postgresql contrib extensions should not be listed, and are working even
without the patches. (This includes for example hstore, dblink,...
see https://www.postgresql.org/docs/current/static/contrib.html for the
full list)
Did not test if it is problem if one adds these to the config though.
2. I had postgis actually missing, due to a missing use module, but there
was no complaint, system reconfigure went just fine, but creating extension
postgis did not work. Can we add some way to check if the list supplied is
sane?
3. contrib extensions also work fine with the patches applied.
4. I did not test if it works if we have more than one extension, but it
looks good.
If we have any other extension packaged, we could take a look.
5. Do you think we should add a test?
6. I got a warning that the first patch introduces whitespace errors on
current master. Is that ok?