Add spec to check string constructed from Array#pack has valid encoding.
Add spec to check string constructed from Array#pack has valid encoding.

kachick/rubyspec,wied03/rubyspec,ruby/spec,nobu/rubyspec,eregon/rubyspec,sgarciac/spec,eregon/rubyspec,nobu/rubyspec,wied03/rubyspec,sgarciac/spec,kachick/rubyspec,ruby/rubyspec,ruby/spec,ruby/rubyspec,ruby/spec,nobu/rubyspec,eregon/rubyspec,sgarciac/spec,wied03/rubyspec,kachick/rubyspec