pgsql: Fix things so that you can still do "select foo()" where foo is a

Log Message:
-----------
Fix things so that you can still do "select foo()" where foo is a SQL
function returning setof record.  This used to work, more or less
accidentally, but I had broken it while extending the code to allow
materialize-mode functions to be called in select lists.  Add a regression
test case so it doesn't get broken again.  Per gripe from Greg Davidson.

Modified Files:
--------------
    pgsql/src/backend/executor:
        execQual.c (r1.249 -> r1.250)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/execQual.c?r1=1.249&r2=1.250)
        functions.c (r1.134 -> r1.135)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/functions.c?r1=1.134&r2=1.135)
    pgsql/src/test/regress/expected:
        rangefuncs.out (r1.21 -> r1.22)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rangefuncs.out?r1=1.21&r2=1.22)
    pgsql/src/test/regress/sql:
        rangefuncs.sql (r1.10 -> r1.11)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/rangefuncs.sql?r1=1.10&r2=1.11)