passing tainted arguments to a C function.
  Patch by sheepman <sheepman AT sheepman.sakura.ne.jp>.

* ext/dl/lib/dl/func.rb (DL::Function#check_safe_obj):
  new method for checking #call's arguments.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@23404 b2dd03c8-39d4-4d8f-98ff-823fe69b080e