Initialize an empty pacman keyring in the target

Use pacstrap -K to create a new pacman keyring instead of copying it from the host. While it gets removed either way in image_cleanup, it seems better to avoid using things from the host.

Please rebase :)

added 3 commits

• 5f9798af...f18ebba7 - 2 commits from branch archlinux:master
• 7884f3ab - Initialize an empty pacman keyring in the target

Compare with previous version

mentioned in commit 83c58570

merged