get_max_ascii_length is mistaken

```
In sig.cpp:
sig_add_address()
{
...
s = get_max_ascii_length(tea, strtype);
...
}

The s value may be more than string's actual length. Therefore, str_hash may 
contain uncertain data so can vary between each running instance.
```

Original issue reported on code.google.com by `shenlian...@gmail.com` on 19 Apr 2013 at 8:58
