use Queue for inter-thread synchronization.

* test/ruby/test_bignum.rb (test_interrupt_during_to_s): should not use
  "while" synchronization, but should use Queue.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63085 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_bignum.rb

@@ -615,14 +615,15 @@ class TestBignum < Test::Unit::TestCase
     start_flag = false
     end_flag = false
     num = (65536 ** 65536)
+    q = Queue.new
     thread = Thread.new do
-      start_flag = true
       assert_raise(RuntimeError) {
+        q << true
         num.to_s
         end_flag = true
       }
     end
-    sleep 0.001 until start_flag
+    q.pop # sync
     thread.raise
     thread.join
     time = Time.now - time