Fix folly::AsyncUDPSocket::gro_.value() check - GRO is enabled if the value is > 0

Summary:
Fix folly::AsyncUDPSocket::gro_.value() check - GRO is enabled if the value is > 0

(Note: this ignores all push blocking failures!)

Reviewed By: kevin-vigor

Differential Revision: D20930544

fbshipit-source-id: 6672b65cafe3f9859f86ad34a6c3a2d65c2dc355

folly/io/async/AsyncUDPSocket.cpp

@@ -689,7 +689,7 @@ void AsyncUDPSocket::handleRead() noexcept {
   ReadCallback::OnDataAvailableParams params;
 
 #ifdef FOLLY_HAVE_MSG_ERRQUEUE
-  if (gro_.has_value() && (gro_ != 0)) {
+  if (gro_.has_value() && (gro_.value() > 0)) {
     char control[CMSG_SPACE(sizeof(uint16_t))] = {};
     struct msghdr msg = {};
     struct iovec iov = {};