update package gnutls
update package libpng
update package isl
update package cloog
Merge commit '25aafac4f932b6cf44b6a9a44c1b9a800db34f4a' into my

* commit '25aafac4f932b6cf44b6a9a44c1b9a800db34f4a':
  update package cloog
  update package isl
  update package libpng
  update package gnutls