pgsql: Use CREATE OR REPLACE LANGUAGE in pg_dump to avoid the need for a

Log Message:
-----------
Use CREATE OR REPLACE LANGUAGE in pg_dump to avoid the need for a couple of
significantly uglier kluges that were working around the change in plpgsql's
preinstalled status.

Modified Files:
--------------
pgsql/src/bin/pg_dump:
pg_dump.c (r1.572 -> r1.573)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c?r1=1.572&r2=1.573)