parse.y: use rb_str_ellipsize
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45761 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
parse.y: use rb_str_ellipsize
get rid of incomplete multibyte sequence.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45761 b2dd03c8-39d4-4d8f-98ff-823fe69b080e