Fix platform dependant regression output triggered by
69f4b9c85f16.
Due to the changed costing in that commit hash-aggregates started to
be used, which results in big-endian vs. little-endian output
differences. Disable hash-aggs for those tests.
Author: Andres Freund, with input from Tom Lane
Discussion: https://postgr.es/m/22891.
1484791792@sss.pgh.pa.us