Tests: Fix numactl on WSL2

test_regress/t/t_bench_mux4k_onecpu.pl

@@ -17,7 +17,10 @@ compile(
                  $Self->wno_unopthreads_for_few_cores()]
     );
 
-if (`numactl --show` !~ /cpu/) {
+# WSL2 gives a warning and we must skip the test:
+#  "physcpubind: 0 1 2 3 ...\n No NUMA support available on this system."
+my $nout = `numactl --show`;
+if ($nout !~ /cpu/ || $nout =~ /system does not support NUMA/i) {
     skip("No numactl available");
 } else {
     execute(