pgsql: Remove typename from A_Const.

Log Message:
-----------
Remove typename from A_Const.

Brendan Jurd, minor editorialization by me.

Modified Files:
--------------
    pgsql/src/backend/nodes:
        copyfuncs.c (r1.392 -> r1.393)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/copyfuncs.c?r1=1.392&r2=1.393)
        equalfuncs.c (r1.321 -> r1.322)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/equalfuncs.c?r1=1.321&r2=1.322)
        outfuncs.c (r1.325 -> r1.326)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/outfuncs.c?r1=1.325&r2=1.326)
    pgsql/src/backend/parser:
        gram.y (r2.612 -> r2.613)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y?r1=2.612&r2=2.613)
        parse_expr.c (r1.227 -> r1.228)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_expr.c?r1=1.227&r2=1.228)
        parse_target.c (r1.159 -> r1.160)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_target.c?r1=1.159&r2=1.160)
        parse_type.c (r1.95 -> r1.96)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_type.c?r1=1.95&r2=1.96)
        parse_utilcmd.c (r2.12 -> r2.13)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_utilcmd.c?r1=2.12&r2=2.13)
    pgsql/src/backend/utils/misc:
        guc.c (r1.447 -> r1.448)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c?r1=1.447&r2=1.448)
    pgsql/src/include/catalog:
        catversion.h (r1.452 -> r1.453)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.452&r2=1.453)
    pgsql/src/include/nodes:
        parsenodes.h (r1.362 -> r1.363)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/parsenodes.h?r1=1.362&r2=1.363)