func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
	_, err := fcntl(int(fd), cmd, int(uintptr(unsafe.Pointer(lk))))
	return err
}
FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
package unix
import "unsafe"
func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
	return fcntl(int(fd), cmd, arg)
}