pgsql: Add PL/pgSQL SQLSTATE and SQLERRM support which sets these values

Log Message:
-----------
Add PL/pgSQL SQLSTATE and SQLERRM support which sets these values on
error.

Pavel Stehule

Modified Files:
--------------
    pgsql/doc/src/sgml:
        plpgsql.sgml (r1.67 -> r1.68)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/plpgsql.sgml.diff?r1=1.67&r2=1.68)
    pgsql/src/pl/plpgsql/src:
        gram.y (r1.69 -> r1.70)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/gram.y.diff?r1=1.69&r2=1.70)
        pl_exec.c (r1.138 -> r1.139)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c.diff?r1=1.138&r2=1.139)
        plpgsql.h (r1.58 -> r1.59)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/plpgsql.h.diff?r1=1.58&r2=1.59)
    pgsql/src/test/regress/expected:
        plpgsql.out (r1.28 -> r1.29)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/plpgsql.out.diff?r1=1.28&r2=1.29)
    pgsql/src/test/regress/sql:
        plpgsql.sql (r1.23 -> r1.24)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/plpgsql.sql.diff?r1=1.23&r2=1.24)