[Bug other/61439] contrib/download_prerequisites script does not verify integrity of packages

[moritz at klammler dot eu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61439

--- Comment #7 from Moritz Klammler <moritz at klammler dot eu> ---
https://gcc.gnu.org/ml/gcc-patches/2016-09/msg00606.html