* transcode_data.h (rb_transcoding): add feedlen field.
* transcode.c (transcode_restartable0): renamed from
transcode_restartable.
save input buffer into feed buffer if next character is started the
point before input buffer. for example, "\x00\xd8\x01" then "\x02"
in UTF-16LE. \x02 causes invalid and next character is started from
\x01.
(transcode_restartable): new function to call
transcode_restartable0. if feed buffer is not empty, convert it at
first.
git-svn-id: http://svn.ruby-lang.org/repos/ruby/trunk@18467 b2dd03c8-39d4-4d8f-98ff-823fe69b080e