* benchmark/driver.rb: define File::NULL if not defiend and /dev/null

  is available to run benchmark driver on ruby 1.9.2.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45832 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 0 deletions

diff --git a/benchmark/driver.rb b/benchmark/driver.rb
index cbc72cf604..a8b524d926 100644
--- a/benchmark/driver.rb
+++ b/benchmark/driver.rb
@@ -238,6 +238,12 @@ class BenchmarkDriver
     result
   end
 
+  unless defined?(File::NULL)
+    if File.exist?('/dev/null')
+      File::NULL = '/dev/null'
+    end
+  end
+
   def measure executable, file
     cmd = "#{executable} #{@ruby_arg} #{file}"