[arch-general] Kernel source URL change

[Konstantin Shalygin]

> Also now to build the package locally you download the whole repository
> (~2 Gb compared to the ~110 Mb previously).

Oh...


Cloning into bare repository '/tmp/4.17-arch/archlinux-linux'...
remote: Counting objects: 6135977, done.
remote: Compressing objects: 100% (1099/1099), done.
remote: Total 6135977 (delta 984), reused 385 (delta 385), pack-reused 
6134493
Receiving objects: 100% (6135977/6135977), 2.07 GiB | 1.03 MiB/s, done.
Resolving deltas: 100% (5111928/5111928), done.


33 minutes to fetch kernel.

If this changeset is good for arch infrastructure builds, may be tar.xz 
will be also provided, via github releases for example.




k