pgsql: Fix broken compare function for tsquery_ops.

Log Message:
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Fix broken compare function for tsquery_ops. Per Tom's report.

I never understood why initial authors GiST in pgsql choose so
stgrange signature for 'same' method:
bool *sameFn(Datum a, Datum b, bool* result)
instead of simple, logical
bool sameFn(Datum a, Datum b)
This change will break any existing GiST extension, so we still live with
it and will live.

Modified Files:
--------------
    pgsql/src/backend/utils/adt:
        tsquery_gist.c (r1.5 -> r1.6)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/tsquery_gist.c?r1=1.5&r2=1.6)