internal/pkg: exclusive artifacts

This alleviates scheduler overhead when curing many artifacts.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/libexpat.go

@@ -11,7 +11,7 @@ func (t Toolchain) newLibexpat() pkg.Artifact {
 		version  = "2.7.3"
 		checksum = "GmkoD23nRi9cMT0cgG1XRMrZWD82UcOMzkkvP1gkwSFWCBgeSXMuoLpa8-v8kxW-"
 	)
-	return t.New("libexpat-"+version, []pkg.Artifact{
+	return t.New("libexpat-"+version, false, []pkg.Artifact{
 		t.Load(Make),
 		t.Load(Bash),
 	}, nil, nil, `