* string.c: check str_strlen's argument, and add comment or
  use NULL if simply it uses str's enc.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45619 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* string.c: use uintptr_t instead of VALUE because they are not ruby
  object.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45620 b2dd03c8-39d4-4d8f-98ff-823fe69b080e