Add testAsync to ThriftTest.thrift which verifies async void works properly.

Summary:
  - testAsync takes a number of seconds to sleep. The test client makes sure
    that the RPC returns in less than 0.2 seconds even though it asks the server
    to sleep for 3 seconds.
  - Implemented this test for C++ and Java.

Test Plan:
  - ran cpp TestServer and TestClient and verified functionality
  - tested cpp and java test server/client against each other - tests passed


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665484 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/test/ThriftTest.thrift b/test/ThriftTest.thrift
index 9056465..a549fa7 100644
--- a/test/ThriftTest.thrift
+++ b/test/ThriftTest.thrift
@@ -90,6 +90,9 @@
   /* Multiple exceptions specifier */
 
   Xtruct testMultiException(string arg0, string arg1) throws(Xception err1, Xception2 err2)
+
+  /* Test async void */
+  async void testAsync(1:i32 secondsToSleep)
 }
 
 service SecondService