benchmark/vm1_ensure.yml: rollback loop_count abstraction

for now.

When measured script is really too fast, while loop substituion may
return a negative benchmark result.

Probably benchmark_driver.gem has rooms to be improved about this.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

benchmark/vm1_ensure.yml

@@ -1,9 +1,14 @@
+# Not utilizing loop_count since using it for this is too unstable for now
 benchmark:
   vm1_ensure: |
-    begin
+    i = 0
+    while i<30_000_000
+      i += 1
       begin
+        begin
+        ensure
+        end
       ensure
       end
-    ensure
     end
-loop_count: 30000000
+loop_count: 1