Add a system test to check the mk and ninja files generated by incremental build.

Bug: 358428180
Test: Run the test locally.
Change-Id: If1862ee44976216f3c5a5c62d50c6d688d38023b
diff --git a/android/init.go b/android/init.go
index d5b486b..b462292 100644
--- a/android/init.go
+++ b/android/init.go
@@ -18,5 +18,6 @@
 
 func init() {
 	gob.Register(ModuleOutPath{})
+	gob.Register(PhonyPath{})
 	gob.Register(unstableInfo{})
 }