THRIFT-1642 pull in patch from Jira to fix signedness issue in timeout calculation

This closes #485
diff --git a/lib/cpp/src/thrift/transport/TSocket.cpp b/lib/cpp/src/thrift/transport/TSocket.cpp
index cc4dce0..4156d7e 100644
--- a/lib/cpp/src/thrift/transport/TSocket.cpp
+++ b/lib/cpp/src/thrift/transport/TSocket.cpp
@@ -564,7 +564,7 @@
       THRIFT_GETTIMEOFDAY(&end, NULL);
       uint32_t readElapsedMicros
           = static_cast<uint32_t>(((end.tv_sec - begin.tv_sec) * 1000 * 1000)
-                                  + (((uint64_t)(end.tv_usec - begin.tv_usec))));
+                                + (end.tv_usec - begin.tv_usec));
 
       if (!eagainThresholdMicros || (readElapsedMicros < eagainThresholdMicros)) {
         if (retries++ < maxRecvRetries_) {