pgsql: Show aggregate return types in psql \da output.

Log Message:
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Show aggregate return types in psql \da output.

Greg Sabino Mullane

Modified Files:
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pgsql/doc/src/sgml/ref:
psql-ref.sgml (r1.188 -> r1.189)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/psql-ref.sgml.diff?r1=1.188&r2=1.189)
pgsql/src/bin/psql:
describe.c (r1.152 -> r1.153)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/describe.c.diff?r1=1.152&r2=1.153)