TODO-RELEASE: libidn problem not repeatable

"261 - configure and libidn" is removed from the list since Julien
Chaffraix tried to repeat it but failed and the reporter did not return
to provide further details.

Reported by: Lyndon Hill
Bug: http://curl.haxx.se/mail/lib-2010-07/0029.html

TODO-RELEASE

 To be addressed in 7.21.2
 =========================
 
-261 -  configure and libidn
-
 268 - 3076430 SFTP resume with 4GB file does not work
 
 271 -