test_rinda.rb: use spawn

* test/rinda/test_rinda.rb (TupleSpaceProxyTest#test_take_bug_8215):
  use more portable spawn instead of fork.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40358 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-04-19

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40359 b2dd03c8-39d4-4d8f-98ff-823fe69b080e