Add trace output when recompilation queues are flushed.

R=mvstanton@chromium.org
BUG=

Review URL: https://codereview.chromium.org/24466003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16945 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/optimizing-compiler-thread.cc

@@ -172,6 +172,9 @@ void OptimizingCompilerThread::Flush() {
   stop_semaphore_.Wait();
   FlushOutputQueue(true);
   if (FLAG_concurrent_osr) FlushOsrBuffer(true);
+  if (FLAG_trace_concurrent_recompilation) {
+    PrintF("  ** Flushed concurrent recompilation queues.\n");
+  }
 }