message: elle.asio: really fix the warnings
diff: # include <winsock2.h>
  #endif
  -#if defined __GCC__
  +#if defined __GNUC__
  # pragma GCC diagnostic push
  // /usr/include/sys/poll.h:1:2: warning: #warning redirecting incorrect #include <sys/poll.h> to <poll.h> [-Wcpp]
  