Revert^6 "Add TARGET_SYSTEM_PROP to system build.prop"

530c32acbee136ff3475192335cc7594589de096

Change-Id: I9dc817855e3db7b96320a977b24b84d72e762893
diff --git a/android/variable.go b/android/variable.go
index df0e59c..00dcbc4 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -507,6 +507,8 @@
 	OemProperties []string `json:",omitempty"`
 
 	ArtTargetIncludeDebugBuild *bool `json:",omitempty"`
+
+	SystemPropFiles []string `json:",omitempty"`
 }
 
 type PartitionQualifiedVariablesType struct {