cl.PkgLinkOnly; llgoRoot, llgoPkgLinkFile

cl/compile.go

@@ -123,6 +123,7 @@ const (
 	PkgLLGo
 	PkgNoInit   // noinit: a package that don't need to be initialized
 	PkgDeclOnly // decl: a package that only have declarations
+	PkgLinkOnly // link: a package that don't need to be compiled but need to be linked
 )
 
 type pkgInfo struct {

cl/import.go

@@ -58,6 +58,8 @@ func PkgKindOf(pkg *types.Package) int {
 // noinit: a package that does not need to be initialized
 func pkgKind(v string) int {
 	switch v {
+	case "link":
+		return PkgLinkOnly
 	case "decl":
 		return PkgDeclOnly
 	case "noinit":