Doesn't correct check ft_strnew

Not correct, but successful checked by 42filechecker end validated by MOULINETTE :

```
char	*ft_strnew(size_t size)
{
	char *str;

	if ((str = (char*)malloc(++size)) == 0)
		return (NULL);
	while (size)
	{
		*(str + size) = '\0';
		size--;
	}
	*str = '\0';
	return (str);
}
```
PS problem in ++size