pgsql: Pass incompletely-transformed aggregate argument lists as

Log Message:
-----------
Pass incompletely-transformed aggregate argument lists as separate parameters
to transformAggregateCall, instead of abusing fields in Aggref to carry them
temporarily.  No change in functionality but hopefully the code is a bit
clearer now.  Per gripe from Gokulakannan Somasundaram.

Modified Files:
--------------
    pgsql/src/backend/parser:
        parse_agg.c (r1.92 -> r1.93)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_agg.c?r1=1.92&r2=1.93)
        parse_func.c (r1.222 -> r1.223)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_func.c?r1=1.222&r2=1.223)
    pgsql/src/include/parser:
        parse_agg.h (r1.42 -> r1.43)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/parser/parse_agg.h?r1=1.42&r2=1.43)