* thread.c: clear thread structure.

(TODO: survey that child process should clear mutex or not).
* bootstraptest/test_knownbug.rb, test_thread.rb: move a fixed test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15044 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

bootstraptest/test_thread.rb

@@ -193,3 +193,11 @@ rescue
   100
 end
 }, '[ruby-dev:31371]'
+assert_equal 'true', %{
+  t = Thread.new { loop {} }
+  pid = fork {
+      exit t.status != "run"
+  }
+  Process.wait pid
+  $?.success?
+}