win32: UTF-8 spawn

* test/ruby/test_process.rb (test_spawn_nonascii): assertions for
  non-ascii arguments.  [ruby-core:24309] [Bug #1771]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41712 b2dd03c8-39d4-4d8f-98ff-823fe69b080e