flambda-backend: Tag unboxed-primitive-args as flambda-only.

testsuite/tests/unboxed-primitive-args/test.ml

@@ -2,19 +2,21 @@
 
 readonly_files = "common.mli common.ml test_common.c test_common.h"
 
-* setup-ocamlopt.opt-build-env
-** ocaml
+* flambda2
+** setup-ocamlopt.opt-build-env
+*** ocaml
 test_file = "${test_source_directory}/gen_test.ml"
 ocaml_script_as_argument = "true"
 arguments = "c"
 compiler_output = "stubs.c"
-*** ocaml
+**** ocaml
 arguments = "ml"
 compiler_output = "main.ml"
-**** ocamlopt.opt
+***** ocamlopt.opt
 ocamlopt_flags = "-extension simd -cc '${cc} -msse4.2'"
 all_modules = "test_common.c stubs.c common.mli common.ml test0.ml test1.ml main.ml"
-***** run
-****** check-program-output
+****** run
+******* check-program-output
 
 *)
+(* We use flambda2 above as a proxy to indicate SIMD is supported *)