message: Remove MSG_WAITFORONE.
  Summary: This isn't relevant for non-blocking sockets.
diff: namespace fsp = folly::portability::sockets;
  -#ifndef MSG_WAITFORONE
  -#define RECVMMSG_FLAGS 0
  -#else
  -#define RECVMMSG_FLAGS MSG_WAITFORONE
  -#endif
  -
  namespace quic {
  QuicClientTransport::QuicClientTransport(
  @@ -1199,8 +1193,7 @@ void QuicClientTransport::recvMmsg(
  #endif
  }
  - int numMsgsRecvd =
  - sock.recvmmsg(msgs.data(), numPackets, RECVMMSG_FLAGS | flags, nullptr);
  + int numMsgsRecvd = sock.recvmmsg(msgs.data(), numPackets, flags, nullptr);
  if (numMsgsRecvd < 0) {
  if (errno == EAGAIN || errno == EWOULDBLOCK) {
  // Exit, socket will notify us again when socket is readable.
  