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/app_mandelbrot.rb

@@ -0,0 +1,23 @@
+require 'complex'
+
+def mandelbrot? z
+  i = 0
+  while i<100
+    i += 1
+    z = z * z
+    return false if z.abs > 2
+  end
+  true
+end
+
+ary = []
+
+(0..1000).each{|dx|
+  (0..1000).each{|dy|
+    x = dx / 50.0
+    y = dy / 50.0
+    c = Complex(x, y)
+    ary << c if mandelbrot?(c)
+  }
+}
+