* ext/-test-/num2int/num2int.c: Return string for result, instead of
  printing.

* test/-ext-/num2int/test_num2int.rb: updated to follow above change.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40036 b2dd03c8-39d4-4d8f-98ff-823fe69b080e