Fix behaviour of 'package_repo update':

* Instead of copying over the repository info from the source 
  repository, we need to read the repository info from a repository 
  info file corresponding to the target repository. Among other 
  problems, copying over the repository info from the source repo 
  put the wrong repository URL into the new repository, which in
  turn caused the package resolution done by Haiku's build system to
  fail (it tried to download packages from the wrong URL).
Additionally, I have updated the incorrect repository on the server, so
building Haiku-x86 should work again.