tests: fix mac-taskpolicy handling in benchmarks on Darwin

Fixed a bug introduced in PR #449, where the exec_wrapper variable was no longer in scope.
This caused the script to abort if --mac-taskpolicy was provided, as it attempted
to check the value of exec_wrapper.

Signed-off-by: Thing-han, Lim <[email protected]>

scripts/lib/mlkem_test.py

@@ -602,11 +602,7 @@ def bench(
             output = False
 
         if mac_taskpolicy:
-            if exec_wrapper:
-                logging.error(f"cannot set both --mac-taskpolicy and --exec-wrapper")
-                sys.exit(1)
-            else:
-                exec_wrapper = f"taskpolicy -c {mac_taskpolicy}"
+            self.cmd_prefix.extend(["taskpolicy", "-c", f"{mac_taskpolicy}"])
 
         # NOTE: We haven't yet decided how to output both opt/no-opt benchmark results
         if self.opt.lower() == "all":
@@ -713,19 +709,27 @@ def all(opt: bool):
 
     def cbmc(self, k):
         config_logger(self.verbose)
+
         def run_cbmc(mlkem_k):
             envvars = {"MLKEM_K": mlkem_k}
             cpucount = os.cpu_count()
             p = subprocess.Popen(
-                ["python3", "run-cbmc-proofs.py", "--summarize",  "--no-coverage", f"-j{cpucount}"],
+                [
+                    "python3",
+                    "run-cbmc-proofs.py",
+                    "--summarize",
+                    "--no-coverage",
+                    f"-j{cpucount}",
+                ],
                 cwd="cbmc/proofs",
                 env=os.environ.copy() | envvars,
             )
             p.communicate()
             assert p.returncode == 0
+
         if k == "ALL":
             run_cbmc("2")
             run_cbmc("3")
             run_cbmc("4")
-        else: 
+        else:
             run_cbmc(k)