string.c: fix potential bug in String#split
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59673 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
string.c: fix potential bug in String#split
matches a octet in the middle of a multi-byte character sequence.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59673 b2dd03c8-39d4-4d8f-98ff-823fe69b080e