Fix debugging for hwui caches

Debugging code attempted to delete a stack item.

Also, the flag fields weren't exactly clear, so rewrite it so it's
clear that kDebugMoreCaches is a combined flag.

Change-Id: If42b7f0f754919343301da5656aee5943cc9bd4a
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 7c10518..47049e2 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -43,7 +43,7 @@
     kDebugDisabled = 0,
     kDebugMemory = 1,
     kDebugCaches = 2,
-    kDebugMoreCaches = 3
+    kDebugMoreCaches = kDebugMemory | kDebugCaches
 };
 
 // These properties are defined in mega-bytes