Make "overrides" attribute of Android_app overridable

Move overrides attribute from appProperties to overridableAppProperties

Bug: 220029162
Test: m
Change-Id: I6f527df3173f142311734333ad37018c83d5e279
diff --git a/java/androidmk.go b/java/androidmk.go
index b930441..60cd7bc 100644
--- a/java/androidmk.go
+++ b/java/androidmk.go
@@ -430,8 +430,8 @@
 
 func (a *AndroidApp) getOverriddenPackages() []string {
 	var overridden []string
-	if len(a.appProperties.Overrides) > 0 {
-		overridden = append(overridden, a.appProperties.Overrides...)
+	if len(a.overridableAppProperties.Overrides) > 0 {
+		overridden = append(overridden, a.overridableAppProperties.Overrides...)
 	}
 	// When APK name is overridden via PRODUCT_PACKAGE_NAME_OVERRIDES
 	// ensure that the original name is overridden.