slirp: Silence warning on Haiku

Haiku has O_BINARY in fcntl.h.
Signed-off-by: NAndreas Färber <andreas.faerber@web.de>
Cc: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

slirp/slirp.h

@@ -24,7 +24,9 @@ typedef char *caddr_t;
 #else
 # define ioctlsocket ioctl
 # define closesocket(s) close(s)
-# define O_BINARY 0
+# if !defined(__HAIKU__)
+#  define O_BINARY 0
+# endif
 #endif
 
 #include <sys/types.h>