[build2] Arch Linux - build2-toolchain added in AUR

[Boris Kolpackov]

Filipe Verri <filipeverri at gmail.com> writes:
 
> The packages are all available in AUR. They can be installed individually:
> - libbutl: https://aur.archlinux.org/packages/libbutl
> - build2: https://aur.archlinux.org/packages/build2
> - libbpkg: https://aur.archlinux.org/packages/libbpkg
> - bpkg: https://aur.archlinux.org/packages/bpkg
> or using the meta package:
> - build2-toolchain: https://aur.archlinux.org/packages/build2-toolchain

Great work, thanks!

Boris