Don't declare sleep.

src/libraries/libisc-new/src/isc_tcp.c

@@ -51,7 +51,6 @@ extern int listen(int, int);
 /*extern int bind(int, struct sockaddr *, int);*/
 extern int close(int);
 /*extern int atoi(const char *str);*/
-extern time_t sleep(time_t);
 /*extern int accept(int fd, struct sockaddr *sock, int *len);*/