THRIFT-3704 Treat the case where we are not able to refill the buffer the same as the EOL case.

Client: C++
Transport: HTTP
diff --git a/lib/cpp/src/thrift/transport/THttpTransport.cpp b/lib/cpp/src/thrift/transport/THttpTransport.cpp
index a466ff6..f93df23 100644
--- a/lib/cpp/src/thrift/transport/THttpTransport.cpp
+++ b/lib/cpp/src/thrift/transport/THttpTransport.cpp
@@ -212,7 +212,7 @@
   httpBuf_[httpBufLen_] = '\0';
 
   if (got == 0) {
-    throw TTransportException("Could not refill buffer");
+    throw TTransportException(TTransportException::END_OF_FILE, "Could not refill buffer");
   }
 }