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

530c32acbee136ff3475192335cc7594589de096

Change-Id: I9dc817855e3db7b96320a977b24b84d72e762893
diff --git a/android/config.go b/android/config.go
index 6948461..f2bf8b0 100644
--- a/android/config.go
+++ b/android/config.go
@@ -2101,3 +2101,7 @@
 
 	return Bool(c.productVariables.Eng)
 }
+
+func (c *config) SystemPropFiles(ctx PathContext) Paths {
+	return PathsForSource(ctx, c.productVariables.SystemPropFiles)
+}