HPCC-12917 Regression suite test topn.ecl doesn't test topn

Compiler optimizations are too clever.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>

testing/regress/ecl/topn.ecl

@@ -16,7 +16,7 @@
 ############################################################################## */
 
 
-i := dataset([{1}, {3}, {5}, {7}, {9}, {2}, {4}, {6}, {8}, {10}], {unsigned1 d});
+i := nofold(dataset([{1}, {3}, {5}, {7}, {9}, {2}, {4}, {6}, {8}, {10}], {unsigned1 d}));
 s := sort(i, d);
 
 output(choosen(sort(i, d+1), 1));