Fix Snapshot::resetClip to also reset the clip region

Change-Id: I979151e73f64ff9d45f8a5232d8700361b09fbc7
diff --git a/libs/hwui/Snapshot.cpp b/libs/hwui/Snapshot.cpp
index 22c7dde..87ed825 100644
--- a/libs/hwui/Snapshot.cpp
+++ b/libs/hwui/Snapshot.cpp
@@ -184,6 +184,7 @@
 
 void Snapshot::resetClip(float left, float top, float right, float bottom) {
     clipRect = &mClipRectRoot;
+    clipRegion = &mClipRegionRoot;
     setClip(left, top, right, bottom);
 }