Tweak setivar to work both with or without ractors

Author: etiennebarrie

benchmarks/setivar.rb

@@ -30,6 +30,13 @@ def set_value_loop
 
 obj = TheClass.new
 
-run_benchmark(1000) do
-  obj.set_value_loop
+if ENV["YJIT_BENCH_RACTOR_HARNESS"]
+  # same code as below, just pass obj as a ractor arg
+  run_benchmark(1000, ractor_args: [obj]) do |_, object|
+    object.set_value_loop
+  end
+else
+  run_benchmark(1000) do
+    obj.set_value_loop
+  end
 end