pgsql: Fixed incorrect argument handling in SET command if argument is a

Log Message:
-----------
Fixed incorrect argument handling in SET command if argument is a variable.

Modified Files:
--------------
    pgsql/src/interfaces/ecpg:
        ChangeLog (r1.384 -> r1.385)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ChangeLog?r1=1.384&r2=1.385)
    pgsql/src/interfaces/ecpg/preproc:
        preproc.y (r1.369 -> r1.370)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/preproc.y?r1=1.369&r2=1.370)
    pgsql/src/interfaces/ecpg/test/expected:
        sql-show.c (r1.13 -> r1.14)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/sql-show.c?r1=1.13&r2=1.14)
        sql-show.stderr (r1.8 -> r1.9)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/sql-show.stderr?r1=1.8&r2=1.9)
        sql-show.stdout (r1.3 -> r1.4)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/sql-show.stdout?r1=1.3&r2=1.4)
    pgsql/src/interfaces/ecpg/test/sql:
        show.pgc (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/sql/show.pgc?r1=1.2&r2=1.3)