build: add FlagDir variable in prebuild code.

pkg/prebuild/prebuild.go

@@ -13,11 +13,13 @@ var (
 	DistDir       *paths.Path
 	Root          *paths.Path
 	RootApparmord *paths.Path
+	FlagDir       *paths.Path
 )
 
 func init() {
 	DistDir = paths.New("dists")
 	Root = paths.New(".build")
+	FlagDir = DistDir.Join("flags")
 	RootApparmord = Root.Join("apparmor.d")
 	Distribution = getSupportedDistribution()
 }

pkg/prebuild/prepare.go

@@ -135,7 +135,7 @@ func Configure() (err error) {
 // Set flags on some profiles according to manifest defined in `dists/flags/`
 func SetFlags() error {
 	for _, name := range []string{"main.flags", Distribution + ".flags"} {
-		path := DistDir.Join("flags", name)
+		path := FlagDir.Join(name)
 		if !path.Exist() {
 			continue
 		}