string.c: keep source code range

* string.c (rb_enc_cr_str_buf_cat): keep code range of the source
  string even if code range of the destination string is unknown.
  no reason to the former is affected by the latter.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45581 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
string.c: reduce function calls

* string.c (rb_enc_cr_str_buf_cat): reduce invariant function
  calls of rb_enc_from_index.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-04-14

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45583 b2dd03c8-39d4-4d8f-98ff-823fe69b080e