internal/rosa: create metadata alongside artifact

This enables deferring evaluation of azalea-based packages and fixes the longstanding quirk of version being disjoint from other metadata.

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

internal/rosa/libev.go

@@ -14,9 +14,7 @@ func (t Toolchain) newLibev() (pkg.Artifact, string) {
 	), nil, (*MakeHelper)(nil)), version
 }
 func init() {
-	native.MustRegister(&Artifact{
-		f: Toolchain.newLibev,
-
+	native.mustRegister(Toolchain.newLibev, &Metadata{
 		Name:        "libev",
 		Description: "a full-featured and high-performance event loop",
 		Website:     "http://libev.schmorp.de/",