Preserving negative sign in arithmetic-shift.  Fixes issue #208.
Preserving negative sign in arithmetic-shift.  Fixes issue #208.

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