pgsql: Avoid function name conflict when plpgsql and rangefuncs

Log Message:
-----------
Avoid function name conflict when plpgsql and rangefuncs regression tests
execute in parallel. Spotted by Peter.

Modified Files:
--------------
pgsql/src/test/regress/sql:
plpgsql.sql (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/plpgsql.sql.diff?r1=1.31&r2=1.32)
pgsql/src/test/regress/expected:
plpgsql.out (r1.36 -> r1.37)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/plpgsql.out.diff?r1=1.36&r2=1.37)