#include <sys/file.h>
#endif
+#if !defined(NSIG) || defined(M_UNIX) || defined(M_XENIX)
+#include <signal.h>
+#endif
+
+/* XXX If this causes problems, set i_unistd=undef in the hint file. */
+#ifdef I_UNISTD
+# include <unistd.h>
+#endif
+
#if defined(HAS_SOCKET) && !defined(VMS) /* VMS handles sockets via vmsish.h */
# include <sys/socket.h>
# include <netdb.h>