Wait until the callback is called with timeout.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35270 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/openssl/test_ssl_session.rb

@@ -351,9 +351,12 @@ __EOS__
         ssl.connect
         last_client_session = ssl.session
         ssl.close
-        Thread.pass # try to ensure server calls callbacks
-        assert(called.delete(:new))
-        assert(called.delete(:remove))
+        timeout(5) do
+          Thread.pass until called.key?(:new)
+          assert(called.delete(:new))
+          Thread.pass until called.key?(:remove)
+          assert(called.delete(:remove))
+        end
       end
     end
     assert(called[:get1])