Move GenerationCache to the utils directory.

Change-Id: I210ffa8f1d76a102bb7d971c649c20a74d03fbe6
diff --git a/libs/hwui/PathCache.h b/libs/hwui/PathCache.h
index bde0e7d..596dfab 100644
--- a/libs/hwui/PathCache.h
+++ b/libs/hwui/PathCache.h
@@ -22,7 +22,7 @@
 #include <SkPath.h>
 
 #include "Texture.h"
-#include "GenerationCache.h"
+#include "utils/GenerationCache.h"
 
 namespace android {
 namespace uirenderer {