Build was previously failing with
```
/build/file: no valid cabinets found
```
Additonaly, a faster download mirror is used. The downloaded file is not identical to the one from the previous mirror, but the produced result is unchanged.
* make font derivations fixed-output where applicable
* fix dead links
* `stdenv.lib` -> `lib` where `stdenv` is not involved
* remove `meta.platforms = [ unix ]` and `meta.platforms = [ linux ]` because the restriction has no sense for data packages
With these fontconfig files it becomes possible for other packages to
configure font aliases for the Microsoft fonts. If both, for example,
vista-fonts and some package providing an alias for Cambria are
installed then the user may control whether or not the alias is active
by manipulating the package priorities.
