tests for [Bug #9599]

* test/dl/test_{cptr,handle}.rb: tests for [Bug #9599].

* test/fiddle/test_{handle,pointer}.rb: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45299 b2dd03c8-39d4-4d8f-98ff-823fe69b080e