Patch from Lorenzo to avoid memory corruption in bignum sqrt.
Patch from Lorenzo to avoid memory corruption in bignum sqrt.

holmescn/chibi-scheme,norton/chibi-scheme,holmescn/chibi-scheme,holmescn/chibi-scheme,norton/chibi-scheme,norton/chibi-scheme,holmescn/chibi-scheme,norton/chibi-scheme,norton/chibi-scheme,holmescn/chibi-scheme,norton/chibi-scheme