* ext/purelib.rb: get rid of recent feature. [ruby-dev:34864]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@16674 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/purelib.rb

@@ -1,3 +1,10 @@
-if nul = $:.find_index {|path| /\A(?:\.\/)*-\z/ =~ path}
+nul = nil
+$:.each_with_index {|path, index|
+  if /\A(?:\.\/)*-\z/ =~ path
+    nul = index
+    break
+  end
+}
+if nul
   $:[nul..-1] = ["."]
 end