plpgsql functions can return RECORD, per Neil Conway.

doc/src/sgml/plpgsql.sgml

doc/src/sgml/xfunc.sgml

src/pl/plpgsql/src/gram.y

src/pl/plpgsql/src/pl_comp.c

src/pl/plpgsql/src/pl_exec.c

src/test/regress/expected/plpgsql.out

src/test/regress/sql/plpgsql.sql