Only test T16190 with the NCG

T16190 is meant to test a NCG feature. It has already caused spurious
failures in other MRs (e.g. !2165) when LLVM is used.

testsuite/tests/perf/compiler/all.T

@@ -350,7 +350,10 @@ test ('WWRec',
       ['-v0 -O'])
 
 test('T16190',
-      [req_th, collect_compiler_stats()],
+      [ req_th,
+        unless(have_ncg(), skip), # T16190 tests a NCG feature
+        collect_compiler_stats()
+      ],
       multimod_compile,
       ['T16190.hs', '-v0'])