benchmark: drop all bm_ prefix for legacy driver.rb

benchmark/*.rb is only benchmarks now. We don't need prefixes.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63928 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

benchmark/vm_thread_sized_queue.rb

@@ -0,0 +1,20 @@
+require 'thread'
+# on producer, one consumer
+
+n = 1_000_000
+q = Thread::SizedQueue.new(100)
+consumer = Thread.new{
+  while q.pop
+    # consuming
+  end
+}
+
+producer = Thread.new{
+  while n > 0
+    q.push true
+    n -= 1
+  end
+  q.push nil
+}
+
+consumer.join