new Chinese BIG5-HKSCS transcoding (with Tatsuya Mizuno)
* test/ruby/test_transcode.rb: added tests for the above
(with Tatsuya Mizuno)
* enc/big5.c: Added BIG5-HKSCS as a replicate encoding of BIG5
(short term solution, needs more work; with Tatsuya Mizuno)
* tool/transcode-tblgen.rb: made 'pat' directly accessible in
class StrSet
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@24264 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
