test_handle.rb: use -test-/dln/empty
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49157 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_handle.rb: use -test-/dln/empty
which is always a shared object and is not used by others.
[ruby-dev:48629] [Bug #10384]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49157 b2dd03c8-39d4-4d8f-98ff-823fe69b080e