powersploit: Fix misspelled group (blackarch-windwows -> blackarch-windows).
archpwn: Remove updateurl.
archpwn: Substitute $pkgname with actual package names.
Merge branch 'master' of https://github.com/noptrix/blackarch into unstable

Conflicts:
	archpwn/firewalk/PKGBUILD
firewalk: Fix tabs. Change directory in prepare().

makepkg's cwd before it runs each function is not defined by any
documentation so we shouldn't rely on it.