mac osで openssh の 8.3以前をコンパイルしようとすると"compiler cannot create working executables"になる理由

int main(int argc, char **argv) {
char *s, buf[32];

strncpy(buf,"/etc", 32);
s = dirname(buf);
if (!s || strncmp(s, "/", 32) != 0) {
exit(1);
} else {
exit(0);
}
}

struct dirent d;
exit(sizeof(d.d_name)<=sizeof(char));

;
return 0;
}

int i = H_SETSIZE;
el_init("", NULL, NULL, NULL);
exit(0);

;
return 0;
}

char b[5];
snprintf(b,5,"123456789");
exit(b[4]!='\0');

;
return 0;
}

int
main ()
{

pid_t pid;
int fd, ptyfd, ttyfd, status;

pid = fork();
if (pid < 0) { /* failed */
exit(1);
} else if (pid > 0) { /* parent */
waitpid(pid, &status, 0);
if (WIFEXITED(status))
exit(WEXITSTATUS(status));
else
exit(2);
} else { /* child */
close(0); close(1); close(2);
setsid();
openpty(&ptyfd, &ttyfd, NULL, NULL, NULL);
fd = open("/dev/tty", O_RDWR | O_NOCTTY);
if (fd >= 0)
exit(3); /* Acquired ctty: broken */
else
exit(0); /* Did not acquire ctty: OK */
}

;
return 0;
}