Add target expunge to remove archives downloaded from #HEAD
Add target expunge to remove archives downloaded from #HEAD

Archives that are tracking a Git branch can become stale. This target
removes all archives whose repo has 'master' in its name. This might be
a bit too simple, though.

Signed-off-by: Christian <4f88b50bc9dba63c9a7d9e208d4b3ac6f1a52800@citrix.com>

mseri/xs-opam,gaborigloi/xs-opam,xapi-project/xs-opam,mseri/xs-opam,lindig/xs-opam