Warning for missing createlang

I have written a patch to issue an hint if someone tries to create a
function in a language that isn't loaded into the database:

test=> CREATE FUNCTION xx() RETURNS INT AS '
test'> select 1'
test-> LANGUAGE 'plpgsql';
ERROR: language "plpgsql" does not exist
HINT: Perhaps you need to use 'createlang' to load the language into
the database.

I know Peter didn't like this idea in the past, but we are getting too
many people who forget createlang, and with our new HINT tags, it seems
appropriate.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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