Use default app certificate from Make

Bug: 69917341
Test: m checkbuild
Test: framework-res.apk is identical after converting to Soong
Change-Id: I6980afd94ea130740da0defeea045eddc2fc6439
diff --git a/android/variable.go b/android/variable.go
index c8a672e..e8d5c69 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -141,6 +141,8 @@
 	AAPTPreferredConfig *string   `json:",omitempty"`
 	AAPTPrebuiltDPI     *[]string `json:",omitempty"`
 
+	DefaultAppCertificate *string `json:",omitempty"`
+
 	AppsDefaultVersionName *string `json:",omitempty"`
 
 	Allow_missing_dependencies *bool `json:",omitempty"`