internal/rosa: export etc native artifact

This is useful for external container tooling.

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

internal/rosa/rosa.go

@@ -243,7 +243,7 @@ func (t Toolchain) New(
 	case stageGentoo, stageEarly:
 		name += "-boot"
 		support = append(support, extra...)
-		support = append(support, cureEtc{})
+		support = append(support, NewEtc(true))
 		if t.stage == stageEarly {
 			_, a := t.MustLoad(_stage0Dist)
 			support = append(support, a)
@@ -289,7 +289,7 @@ mkdir -vp /work/system/bin
 		}
 
 		support = slices.Concat(extra, t.S.New(t.stage-1).Append([]pkg.Artifact{
-			cureEtc{newIANAEtc()},
+			NewEtc(false),
 		},
 			base,
 			_mksh,