plpsm - plpgpsm: fix bug in execute immediate

Log Message:
-----------
fix bug in execute immediate

Modified Files:
--------------
    plpgpsm/src:
        gram.y (r1.47 -> r1.48)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/gram.y.diff?r1=1.47&r2=1.48)
        pl_comp.c (r1.18 -> r1.19)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/pl_comp.c.diff?r1=1.18&r2=1.19)
        pl_exec.c (r1.47 -> r1.48)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/pl_exec.c.diff?r1=1.47&r2=1.48)
    plpgpsm/src/expected:
        plpgpsm.out (r1.17 -> r1.18)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/expected/plpgpsm.out.diff?r1=1.17&r2=1.18)
    plpgpsm/src/sql:
        plpgpsm.sql (r1.15 -> r1.16)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/sql/plpgpsm.sql.diff?r1=1.15&r2=1.16)