pgsql-server: Still another place to make the world safe for zero-column

Log Message:
-----------
Still another place to make the world safe for zero-column tables:
remove the ancient (and always pretty dodgy) assumption in parse_clause.c
that a query can't have an empty targetlist.

Modified Files:
--------------
    pgsql-server/src/backend/parser:
        analyze.c (r1.299 -> r1.300)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/parser/analyze.c.diff?r1=1.299&r2=1.300)
        parse_clause.c (r1.128 -> r1.129)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/parser/parse_clause.c.diff?r1=1.128&r2=1.129)
    pgsql-server/src/include/parser:
        parse_clause.h (r1.40 -> r1.41)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/parser/parse_clause.h.diff?r1=1.40&r2=1.41)