Add mainline dev certificate dir to config

Bug: 33691272
Test: build
Change-Id: I22aa2f016042eed8555c66a19caeb8967416484d
diff --git a/android/variable.go b/android/variable.go
index 874b69d..86b8c8f 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -249,7 +249,8 @@
 	AAPTPreferredConfig *string  `json:",omitempty"`
 	AAPTPrebuiltDPI     []string `json:",omitempty"`
 
-	DefaultAppCertificate *string `json:",omitempty"`
+	DefaultAppCertificate           *string `json:",omitempty"`
+	MainlineSepolicyDevCertificates *string `json:",omitempty"`
 
 	AppsDefaultVersionName *string `json:",omitempty"`