io.c: fix fptr_copy_finalizer
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62145 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: fix fptr_copy_finalizer
finalizer does not change, pipe_list should not change too.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62145 b2dd03c8-39d4-4d8f-98ff-823fe69b080e