Skip the hang-up test on mingw

Author: nobu

test/ruby/test_thread.rb

@@ -1480,6 +1480,8 @@ def test_thread_native_thread_id_across_fork_on_linux
   end
 
   def test_thread_interrupt_for_killed_thread
+    pend "hang-up" if RUBY_PLATFORM.include?("mingw")
+
     opts = { timeout: 5, timeout_error: nil }
 
     assert_normal_exit(<<-_end, '[Bug #8996]', **opts)