Fix bounds checking in DConfReader
Fix bounds checking in DConfReader

  if a very large size was given then it would cause the pointer
  value to wrap, which means that it would easily compare less than
  the end-of-file pointer.

  check for this.

GNOME/dconf,GNOME/dconf,GNOME/dconf,nekohayo/dconf,GNOME/dconf,nekohayo/dconf