* test/strscan/test_stringscanner.rb: test it.
* re.c: export kcode_set_option and kcode_reset_option (with "rb_" prefix).
* intern.h: ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@11524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e